Material handling system

ABSTRACT

A system may include a vehicle for delivering items and a moveable track that cooperates with the vehicle. The moveable track may cooperate with a storage system having storage locations for storing items. The vehicle may drive into the moveable track and lift the track using a vertical drive mechanism. The vehicle may include a horizontal drive system operable to drive the vehicle horizontally along the ground to carry the moveable track to a position adjacent the storage location. The vehicle may operate the vertical drive system to drop the moveable track adjacent the storage system. Additionally, the vehicle may operate the vertical drive to drive up the moveable track to an elevated position adjacent one of the storage locations in the storage system. The vehicle may include a transfer mechanism for transferring items between the vehicle and the storage location while the vehicle is in the elevated position.

PRIORITY CLAIM

This application is a continuation of co-pending U.S. patent applicationSer. No. 17/564,353 filed Dec. 29, 2021, which is a continuation of U.S.patent application Ser. No. 16/993,301 filed Aug. 14, 2020, now issuedas U.S. Pat. No. 11,254,504, which claims priority under 35 U.S.C. § 119to U.S. Provisional Patent Application No. 62/886,602 filed on Aug. 14,2019. The entire disclosure of each of the foregoing applications ishereby incorporated herein by reference.

FIELD OF THE INVENTION

Embodiments of the present invention generally relate to automatedmaterial and article handling systems which can be used in warehouse,storage and/or distribution environments.

BACKGROUND

Modern material handling systems, such as those used in mail-orderwarehouses, supply chain distribution centers, and custom-ordermanufacturing facilities, face significant challenges in responding torequests for inventory articles. In their incipiency, enterprises willgenerally invest in a level of automation that is at least adequate forcurrent needs. As the scale of an inventory management system expands toaccommodate a greater number and variety of articles, however, so toodoes the cost and complexity of operating it to simultaneously completethe packing, storing, replenishment, and other inventory managementtasks for which it is intended.

Failure to efficiently utilize resources such as space, equipment, andmanpower in an inventory management facility results in lowerthroughput, longer response times, and a growing backlog of unfinishedtasks. Greater efficiency may often be achieved, for a time, byincrementally expanding the capacity of the facility's existingautomation infrastructure, particularly when that expansion follows awell-conceived plan for growth. Sooner or later, however, a point ofdiminishing returns is encountered. That is, the achievement of furthergains in capacity and/or functionality eventually becomes costprohibitive as compared to available alternatives, if such gains can berealized at all. When that point of diminishing returns is reached, afacility operator may be forced to abandon pre-existing materialhandling infrastructure and to replace that infrastructure with acompletely new automation platform.

SUMMARY OF THE INVENTION

The present invention provides a number of inventive aspects that relateto material handling and/or storage and retrieval processes.

According to one aspect, a method for delivering items to a storageassembly having a plurality of storage locations is provided. The methodincludes the step of providing a vehicle having a first drive system fordriving the vehicle in a horizontal direction and a second drive system.A moveable track is provided having an opening configured to receive aportion of the vehicle. The first drive system is actuated to drive thevehicle along a horizontal surface to a position adjacent the moveabletrack. The vehicle is aligned with the opening in the moveable track. Atleast a portion of the vehicle is driven into the opening. The seconddrive system is actuated to raise the moveable track vertically to liftthe moveable track off the ground. The first drive system is actuated todrive the vehicle with the moveable track in a horizontal directiontoward the storage assembly. The second drive system is actuated todrive the vehicle vertically up the moveable track to a positionadjacent one of the storage locations. An item is transferred betweenthe vehicle and the one storage location while the vehicle is adjacentthe one storage location. Additionally, the second drive system isactuated to drive the vehicle downwardly toward the ground.

According to another aspect, a method is provided for delivering itemsto a storage assembly having a plurality of storage locations. Themethod includes a plurality of steps, which may include the step ofdriving a vehicle along a horizontal surface to a position adjacent amoveable track. The method may also include the step of operating thevehicle to lift the moveable track. Optionally, the method includes thestep of driving the vehicle horizontally to carry the moveable track toa position adjacent the storage assembly. Additionally, the method mayinclude the step of driving the vehicle vertically upwardly along themoveable track to an elevated position. Further, the method optionallyincludes the step of transferring an item between the vehicle and astorage location in the storage assembly while the vehicle is in theelevated position. The method may also include the step of driving thevehicle vertically down the track after the step of transferring anitem.

According to another aspect, a method for delivering items to a storageassembly may include the step of transferring an item from a storagelocation onto a vehicle, wherein the method comprises the step ofdriving the vehicle horizontally with the item to deliver the item to alocation remote from the one storage location.

According to yet another aspect, a method for delivering items to astorage assembly may include a moveable track that comprises a frameconfigured to receive the vehicle and the method may include the step ofdriving the vehicle into the frame.

According to a further aspect, a method for delivering items to astorage assembly may include the step of positioning a vertical drive ofa vehicle in operative engagement with a vertical track of a moveabletrack.

According to an additional aspect, a method for delivering items to astorage assembly may include the step of actuating vertical drive of avehicle to lower a moveable track after a step of actuating horizontaldrive system to drive the vehicle with the moveable track.

According to another aspect, a method for delivering items to a storageassembly may include the step of controlling a vehicle to displace amoveable track to releasably connect the moveable track with the storageassembly. Optionally, the step of connecting may comprise releasablyconnecting the moveable track with the storage assembly to impededisplacement of the moveable track relative to the storage assemblyalong at least one horizontal axis.

According to a further aspect, a method for delivering items to astorage assembly may include a moveable track having a connector and themethod may include the step of driving a horizontal drive of a vehicleto displace the moveable track vertically to connect the connector ofthe moveable track with the storage assembly.

According to an additional aspect, a method for delivering items to astorage assembly may include the step of controlling a vehicle todisconnect a moveable track from the storage assembly. Optionally, thestep of disconnecting comprises vertically displacing the moveabletrack.

According to another aspect, a method for delivering items to a storageassembly may include the step of actuating a vertical drive of a vehicleto raise a moveable track by driving the vertical drive system in afirst direction.

According to a further aspect, a method for delivering items to astorage assembly may include the step of actuating a vertical drive of avehicle to drive the vehicle vertically up by driving the vertical drivesystem in a second direction that is opposite the first direction.

According to another aspect, a method for delivering items to a storageassembly may include the step of actuating a vertical drive system of avehicle to drive the vehicle vertically up while maintaining theorientation of the vehicle relative to the horizon as the vehicle isdriven upwardly. Optionally, the step of maintaining the orientation ofthe vehicle relative to the horizon comprises the step of synchronouslydriving the vertical drive elements.

According to another aspect, a method for delivering items to a storageassembly may include the step of transferring an item between a vehicleand a storage location by actuating a transfer mechanism on the vehicle.Optionally, the step of actuating a transfer mechanism comprisesextending a transfer mechanism horizontally toward the one storagelocation. Optionally, the transfer mechanism may be connected with ahorizontal drive system and the step of actuating a transfer mechanismcomprises driving the horizontal drive system.

According to a further aspect, a method for delivering items to astorage assembly may include the step of actuating a horizontal drivesystem of a vehicle to drive the vehicle with a moveable track bydriving the vehicle horizontally while the moveable track is lifted offthe ground. Optionally, the step of driving the vehicle horizontallywhile the moveable track is lifted off the ground includes the steps ofidentifying a column of the storage assembly in which the one storagelocation is located; and aligning the moveable track with the column sothat a transfer opening in the moveable track aligns with an opening inthe column. Optionally, the step of transferring comprises transferringthe item through the transfer opening.

The present invention provides a number of inventive aspects that relateto material handling systems and/or storage and retrieval systems.

For instance, according to one aspect, the present invention provides amaterial handling system that includes a storage assembly a vehicle anda moveable track. The storage assembly may have a plurality of elevatedstorage locations for storing items. The vehicle may be configured todeliver items to the storage locations and retrieve items from thestorage locations, wherein the vehicle comprises a first drivingassembly for driving the vehicle in a horizontal direction and seconddriving assembly. The moveable may have an opening configured to receivea portion of the vehicle. Additionally, the moveable track may includean element for engaging the second driving system of the vehicle. Theengagement element may cooperate with the second driving system so thatdriving the second driving system in a first direction is operable tolift the moveable track off the ground and so that driving the secondsystem in a second direction is operable to drive the vehicle verticallyupwardly to an elevated position. Optionally, the vehicle is configuredto drive the vehicle along a horizontal surface to a location adjacentthe storage assembly. Additionally, the vehicle may include a transfermeans configured to transfer an item between the vehicle and a storagelocation of the storage assembly while the vehicle is in the elevatedposition adjacent the storage location.

According to another aspect, the present invention provides a materialhandling system cooperable with a storage assembly having a plurality ofstorage locations for storing a plurality of items. The system mayinclude a vehicle and a moveable track. The vehicle may include ahorizontal drive assembly configured to drive the vehicle horizontallyalong the ground and a vertical drive assembly configured to drive thevehicle vertically upwardly. The vehicle may also include a transfermechanism for transferring items between the vehicle and the storagelocations. The vehicle may further include a power source for poweringthe horizontal drive assembly and the vertical drive assembly. Themoveable track optionally includes a vertical track cooperable with thevertical drive assembly of the vehicle and a support structureconfigured to support the vertical track in a vertical orientation. Themoveable track may include an opening configured to receive at least aportion of the vehicle. The vertical drive assembly and the verticaltrack may be configured and positioned so that when the vehicle extendsinto the opening in the moveable track, the vertical drive assemblyengages the vertical track, such that driving the vertical drive in afirst direction is operable to raise the moveable track. Optionally,driving the vertical drive assembly in a second direction may beoperable to drive the vehicle up the track to an elevated position tofacilitate transfer of an item between a storage location and thevehicle. Additionally, the support structure may be configured tosupport the vehicle when the vehicle is in the elevated position on thevertical track.

According to a further aspect, a material handling system may include avehicle and a moveable track having a support structure that includes aframe forming a column having an opening for receiving the vehicle.

According to a further aspect, a material handling system may include amoveable track having a connector for releasably connecting the moveabletrack with a storage assembly. Optionally, the connector is configuredto impede displacement of the moveable track relative to the storageassembly along at least one horizontal axis. Additionally, the connectormay be configured so that relative vertical displacement between themoveable frame and the storage assembly connects the connector with thestorage assembly. Further, the connector may be configured such thatvertical displacement of the connector relative to the storage assemblyis operable to disconnect the moveable track from the storage assembly.

According to a further aspect, a material handling system may include avehicle having a vertical drive system for driving the vehiclevertically up a moveable track and the vertical drive assembly may beconfigured to maintain the orientation of the vehicle relative to thehorizon as the vehicle is driven upwardly. Optionally, the moveabletrack includes a plurality of track sections extending verticallyupwardly and the vertical drive assembly includes a plurality ofvertical drive elements interconnected so that operating the verticaldrive assembly synchronously drives the vehicle up the track sections tomaintain the horizontal orientation of the vehicle.

According to a further aspect, a material handling system may include avehicle having a horizontal drive assembly for driving the vehicle in ahorizontal direction and a transfer mechanism. The transfer mechanismmay be connected with one of the horizontal drive assembly so thatdriving the horizontal drive assembly is operable to drive the transfermechanism away from the vehicle toward a storage location. Optionally,the system includes a clutch for selectively engaging and disengagingthe transfer mechanism with the horizontal drive assembly.

According to another aspect, a material handling system may include avehicle having a vertical drive system and a moveable track having asupport structure. The vertical drive may project outwardly from thevehicle and the support structure may include gaps configured to alignwith the vertical drive system to facilitate the vehicle driving intothe support structure. Optionally, the moveable track includes avertical track and the vertical track has an upper section and a lowersection each including a plurality of teeth configured to cooperate withthe vertical drive assembly. The upper section and lower section mayhave similar pitch between teeth and the lower section may have gapsbetween adjacent teeth to provide clearance to facilitate the verticaldrive driving through the lower section. Optionally, the vertical driveassembly includes a plurality of spur gears having a tooth pitch andeach spur gear is rotatable about an axis. The axes of the spur gear maybe substantially parallel. Additionally, the spacing between the teethof the lower section may provide sufficient clearance for the teeth ofthe spur gears to pass between the gaps when the spur gears translatehorizontally along a line that is parallel to the axis of rotation ofthe spur gears. Optionally, the spur gears and the vertical track areconfigured and positioned so that an addendum circle of the spur gearsoverlaps with the addendum line of the teeth in the track. Additionally,the vertical track may include an upper section and a lower sectionwherein the upper section has an upper tooth profile having an upperroot and an upper dendendum and the lower section has a lower toothprofile having a lower root and a lower dendendum that is greater thanthe upper dedendum so that the lower root of the teeth extends inwardlyaway from the vertical drive assembly a greater distance than the upperroot.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a perspective view of a material handling system;

FIG. 2A is a perspective view of an automated guided of the materialhandling system illustrated in FIG. 1;

FIG. 2B is a plan view of the vehicle illustrated in FIG. 2A;

FIG. 2C is a bottom view of the vehicle illustrated in FIG. 2A;

FIG. 2D is a front elevation view of the vehicle depicted in FIG. 2A;

FIG. 2E is a rear elevation view of the vehicle depicted in FIG. 2A;

FIG. 2F is a side elevation view of the vehicle depicted in FIG. 2A;

FIG. 2G is a plan view of the vehicle illustrated in FIG. 2A with aportion of a rack of the system illustrated in FIG. 1;

FIG. 2H is a cross-sectional taken across line II-H in FIG. 2G;

FIG. 2I is an enlarged fragmentary view of the vehicle and rackillustrated in FIG. 2H;

FIG. 3A is a section view of the vehicle of FIG. 2A taken across lineIIIA-IIIA;

FIG. 3B is partially broken away bottom view of the vehicle of FIG. 2A;

FIG. 4A is a sectional view of the vehicle of FIG. 2A, taken along lineIVA-IVA;

FIG. 4B is a sectional view of the vehicle of FIG. 2A, taken along lineIVA-IVB in FIG. 2A illustrating a clutch mechanism in a disengagedposition;

FIG. 4C is a sectional view of the vehicle of FIG. 4B, illustrating theclutch mechanism in an engaged position;

FIG. 4D is a partially broken away side elevation view of the vehicle ofFIG. 2A, illustrating an actuator mechanism in a first position;

FIG. 4E is a side elevational view of the vehicle of FIG. 4D,illustrating the actuator mechanism in a second position;

FIG. 5A is a side elevation of a moveable rack of the material handlingsystem illustrated in FIG. 1;

FIG. 5B is a front elevational view of the moveable rack illustrated inFIG. 5A;

FIG. 5C is an enlarged fragmentary view of a portion of the moveablerack illustrated in FIG. 5A, partially broken away;

FIG. 5D is an enlarged fragmentary view of a portion of the moveablerack illustrated in FIG. 5A, showing the rack in a raised position;

FIG. 5E is a side elevational view of the moveable rack illustrated inFIG. 5B, illustrating the moveable rack in a raised position;

FIG. 5F is a front elevational view of the moveable rack illustrated inFIG. 5B, illustrating the moveable rack with a vehicle in a raisedposition;

FIG. 6A is an enlarged perspective view of a moveable rack and a flowrack of the material handling system illustrated in FIG. 1 d;

FIG. 6B is a side elevational view of the moveable rack and flow rackillustrated in FIG. 6A;

FIG. 6C is a side elevational view of the moveable rack and flow rackillustrated in FIG. 6B shown in a connected position;

FIG. 6D is a front perspective view of the moveable rack and flow rackillustrated in FIG. 6A;

FIG. 6E is a plan view of the moveable rack and flow rack illustrated inFIG. 6A;

FIG. 6F is an enlarged plan view of a portion of the moveable rack andflow rack illustrated in FIG. 6E;

FIG. 7 is an enlarged fragmentary perspective view of a rack portion ofthe material handling system illustrated in FIG. 1;

FIG. 8 is a front elevational view of an aisle of a rack system of thematerial handling system illustrated in FIG. 1;

FIG. 9 is a side elevational view of the aisle illustrated in FIG. 8;

FIG. 10 is a plan view of the aisle illustrated in FIG. 8;

FIG. 11 is an enlarged fragmentary side elevational view of the aisleillustrated in FIG. 13A;

FIG. 12 is a block diagram depicting the subsystems of a plurality ofguided vehicles according to one or more embodiments; and

FIG. 13 is a block schematic diagram of a controller of the systemillustrated in FIG. 1.

While the systems and methods are described herein by way of example forseveral embodiments and illustrative drawings, those skilled in the artwill recognize that systems and methods for performing respectivesubsets of inventory management tasks using corresponding functionalaccessory modules are not limited to the embodiments or drawingsdescribed. It should be understood that the drawings and detaileddescription thereto are not intended to limit embodiments to theparticular form disclosed. Rather, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the systems and methods for performing respective subsetsof inventory management tasks using corresponding functional accessorymodules defined by the appended claims. Any headings used herein are fororganizational purposes only and are not meant to limit the scope of thedescription or the claims. As used herein, the word “may” is used in apermissive sense (i.e., meaning having the potential to), rather thanthe mandatory sense (i.e., meaning must). Similarly, the words“include”, “including”, and “includes” mean including, but not limitedto.

DETAILED DESCRIPTION OF EMBODIMENTS

Various embodiments of a method and apparatus for performing inventorymanagement tasks in an inventory management system are described. In thefollowing detailed description, numerous specific details are set forthto provide a thorough understanding of claimed subject matter. However,it will be understood by those skilled in the art that claimed subjectmatter may be practiced without these specific details. In otherinstances, methods, apparatuses or systems that would be known by one ofordinary skill have not been described in detail so as not to obscureclaimed subject matter.

Some portions of the detailed description that follow are presented interms of algorithms or symbolic representations of operations on binarydigital signals stored within a memory of a specific apparatus orspecial purpose computing device or platform. In the context of thisparticular specification, the term specific apparatus or the like mayinclude a general-purpose computer once it is programmed to performparticular functions pursuant to instructions from program software.Algorithmic descriptions or symbolic representations are examples oftechniques used by those of ordinary skill in the signal processing orrelated arts to convey the substance of their work to others skilled inthe art. An algorithm is here, and is generally, considered to be aself-consistent sequence of operations or similar signal processingleading to a desired result. In this context, operations or processinginvolve physical manipulation of physical quantities. Typically,although not necessarily, such quantities may take the form ofelectrical or magnetic signals capable of being stored, transferred,combined, compared or otherwise manipulated. It has proven convenient attimes, principally for reasons of common usage, to refer to such signalsas bits, data, values, elements, symbols, characters, terms, numbers,numerals or the like. It should be understood, however, that all ofthese or similar terms are to be associated with appropriate physicalquantities and are merely convenient labels.

Unless specifically stated otherwise, as apparent from the followingdiscussion, it is appreciated that throughout this specificationdiscussions utilizing terms such as “processing,” “computing,”“calculating,” “determining” or the like refer to actions or processesof a specific apparatus, such as a special purpose computer or a similarspecial purpose electronic computing device. In the context of thisspecification, therefore, a special purpose computer or a similarspecial purpose electronic computing device is capable of manipulatingor transforming signals, typically represented as physical electronic ormagnetic quantities within memories, registers, or other informationstorage devices, transmission devices, or display devices of the specialpurpose computer or similar special purpose electronic computing device.

Reference will now be made in detail to exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

Referring now to the figures in general and to FIG. 1 specifically, anapparatus for sorting or retrieving items is designated generally 10.The apparatus 10 includes one or more mechanisms for delivering items toand/or retrieving items from one of a plurality of locations, such asstorage areas located in racks 800 or flow racks 600. The deliverymechanism may include one or more vehicles 200 that transport items. Forinstance, optionally, the vehicles may retrieve items from storagelocations 820 in the racks 800 and deliver the items to a workstation500 where an operator can retrieve the item from the vehicle. Thevehicle may optionally return to a storage area in the rack to store anyremaining items that were not retrieved by the operator. The vehicle canthen advance to another storage area to obtain the next item to beretrieved. In this way, the system may include a mechanism forcontinuously storing and retrieving items to/from the various storageareas so that the items can be presented to an operator. Optionally, aguide, such as a track, may be positioned adjacent the rack so that thevehicle may climb the rack vertically to retrieve an item from the rack.Optionally, the system may include a moveable rack that is configured tobe transported by the vehicles. The vehicles may transport the moveablerack into position adjacent a storage rack. The vehicle may then climbthe rack vertically to transfer items between the vehicle and a storagelocation in the storage rack.

It should be understood that various items and subassemblies of theoverall system can be used alone or in combination with materialhandling systems having different structure or operation to the systemillustrated in the Figures and described below.

As illustrated in FIGS. 1 and 7, the material handling system mayoptionally incorporate one or more storage racks 800. Each storage rackmay include a plurality of storage locations 820. Optionally, thestorage locations may be arranged into one or more vertical columns 810.For instance, FIG. 1 illustrates a plurality of racks 800 and each rackmay include a plurality of columns 810, each of which includes aplurality of storage locations. The items that are handled by the systemmay be stored directly in the storage locations. Alternatively, theitems may be stored in bins or totes 55 and the storage locations 820may be configured to store the totes 55 as shown in FIGS. 1 and 7-9.Accordingly, it should be understood that unless stated otherwise in thefollowing description, when a tote is mentioned, the term tote is broadenough to include a container for containing one or more items as wellas simply being an item that is not necessarily contained in acontainer. Although the present system is described as using totes, itshould be understood that any of a variety of storage mechanisms can beused, such as pallets or similar platforms.

Vehicles

FIGS. 2A-2I illustrate details of one of the vehicles 200 that are shownin FIG. 1. As noted above, if the system incorporates vehicles, thestructure of the vehicle may vary. Accordingly, it should be understoodthat each of the vehicle's features discussed below are optionalfeatures that may be varied or eliminated depending on the application.

The vehicles 200 may be autonomous systems that include an onboard powersupply for driving the vehicle. The vehicles may also include acommunication system for wirelessly receiving and transmitting controlsignals between each vehicle and a control element, such as the centralcontroller 450. In this way, the vehicle may receive control signalsregarding the location for retrieving an item and the location to whichthe vehicle is to deliver the item.

Referring now to FIGS. 2A to 2I, there is shown an automated guidedvehicle 200 constructed in accordance with embodiments of the presentdisclosure and adapted to perform inventory management tasks in, forexample, any of the material handling systems depicted in FIG. 1. Eachdelivery vehicle may be an automated guided vehicle having a firstmotorized drive system and a second motorized drive system, as well asan onboard power supply.

As discussed further below, the vehicle may include a horizontal driveassembly for driving the vehicle 200 in a horizontal direction. Thehorizontal drive may be configured to drive the vehicle along a track oralong an open horizontal surface, such as a floor. For instance, oneoption for a horizontal drive includes a plurality of rotatableelements, such as wheels or rollers. One or more drive mechanisms may beprovided for turning the rotatable elements. Additionally, the rotatableelements may turn from side to side to steer the vehicle.

The vehicle illustrated in FIGS. 2A-4E includes a horizontal driveassembly for driving the vehicle 200 in a horizontal direction. Thehorizontal drive may be configured to drive the vehicle along a track oralong an open horizontal surface, such as a floor. For instance, oneoption for a horizontal drive includes a plurality of rotatableelements, such as wheels or rollers. One or more drive mechanisms may beprovided for turning the rotatable elements. Additionally, the rotatableelements may turn from side to side to steer the vehicle.

As noted above, the vehicle 200 may have any of a variety of steeringmechanisms for controlling the direction of travel of the vehicle. Forexample, an optional steering mechanism is a zero-turn mechanism thatcan turn the vehicle without substantially moving forwardly. Optionally,the zero-turn mechanism provides a means for turning the vehicle about avertical axis extending through the vehicle.

The zero-turn mechanism comprises a linkage that allows the wheels orrollers on one side of the vehicle to rotate at a different speed thanthe wheels or rollers on the opposing side of the vehicle. Optionally,the linkage allows the wheels or rollers on one side of the vehicle torotate in different directions than the wheels or rollers on theopposing side of the vehicle. In this way, by varying the speed and/orrotational direction of the wheels on one side of the vehicle relativeto the speed and/or rotational direction of the wheels on the opposingside of the vehicle, the zero-turn mechanism changes the direction oftravel to steer the vehicle.

For instance, as illustrated in FIGS. 2A-4E, the vehicle may have ahorizontal drive formed of a plurality of rollers 252, 254, 256 that arerotatable around a first axis, such as around an axle. Additionally,each of the rollers 252,254,256 may be constrained to rotation about asingle axis. For example, the horizontal drive may include a pair ofcentral rollers 252 a,b and first and second sets of outer rollers 254a,b, 256 a,b. The first set 254 a,b may be positioned forwardly of thecentral rollers 252 a,b while the second set of rollers 256 a,b may bepositioned rearwardly of the central rollers. Optionally, each set ofouter rollers 254 a,b and 256 a,b may include a pair of rollers on eachside of the vehicle as shown in FIG. 2E.

With particular reference to FIGS. 2C and 2F, the details of thehorizontal drive system will be described. However, it should beunderstood that a variety of elements and configurations can beincorporated to provide a horizontal drive system. Accordingly, thefollowing description is merely one example of a horizontal drivesystem. As shown in FIG. 2C, vehicle 200 further includes a second drivesystem which is dimensioned and arranged to propel vehicle 200 upon anunderlying support surface—such as the floor of a warehouse ordistribution center. In the illustrative embodiment of FIG. 2C, thesecond drive system includes a second motor of vehicle 200, indicatedgenerally at 250 a, and a third motor of vehicle 200, indicatedgenerally at 250 b. By dynamically controlling the relative speed and/ordirection of rotation of each of motors 250 a and 250 b, vehicle 200 canbe driven in any direction upon an underlying support surface, assurface S depicted in FIG. 2F.

With continued reference to FIG. 2C, it will be seen that the seconddrive system of vehicle 200 includes a first drive element 252 a drivenby second motor 250 a to rotate about a first axis of rotation A₁, and asecond drive element 252 b driven by third motor 250 b to rotate about asecond axis of rotation A₂. Each of the first and second drive elements252 a and 252 b is respectively dimensioned and arranged to engage arespective portion of underlying support surface S for movement of thevehicle thereupon. In embodiments of a vehicle exemplified by FIGS. 2Cand 2F, the first axis of rotation A₁ and the second axis of rotation A₂are co-axial while drive elements 252 a and 252 b are supported by aplanar, horizontal surface. In this instance, the second drive system ofvehicles 200 optionally includes a plurality of omnidirectional wheelscomprising a first pair of wheels 254 a and 254 b and a second pair ofwheels 256 a and 256. The omnidirectional wheels may be dimensioned andarranged to frictionally engage respective portions of the underlyingsurface S (FIG. 2F), with each of wheels 254 a, 254 b, 256 a and 256 bbeing secured to a corresponding drive axle as axles 258 a and 258 b,respectively.

With particular reference to FIGS. 2C and 2D to 2F, it will be seen thatthe vehicle 200 may also incorporate a series of guides 233, 235 whichdownwardly depend from shafts. Each of the guides 233 is rotatablymounted to the lower part of a shaft. The guides 233, 235 facilitatealignment of vehicle 212 as it is maneuvered upon an underlying supportsurface and brought into alignment with one or more other structures itmay enter in the course of performing an assigned inventory managementtask. In FIG. 2C, for example, it can be seen that some of the guides233, 235 are arranged along a longitudinal center line L of vehicle 200.FIG. 2E depicts alignment of guide 235 within a pair of parallel rails,shown in cross section and mounted upon underlying support surface S. Inan exemplary application, rails R₁ and R₂ are arranged along a path bywhich vehicle 200 enters, exits, and/or maneuvers beneath a verticalarray of storage cells, as depicted in FIGS. 8-10.

Referring to FIGS. 2A and 2D to 2F, the vertical drive system of vehicle200 optionally includes a plurality of drive elements, such as gears 220that are driven to transport the vehicle along a vertical guide, such asa track. The gears 220 are mounted onto two parallel spaced apart axles215 (see FIG. 2F), so that two of the gears are disposed along theforward edge of the vehicle and two of the gears are disposed along therearward edge of the vehicle.

Turning now to FIGS. 3A and 3B, FIG. 3A is a forward elevation view ofthe exemplary automated guided vehicle of FIGS. 2A-2F, taken in crosssection across line IIIA-IIIA in FIG. 2A, and FIG. 3B is bottom planview of the exemplary automated guided vehicle FIGS. 2A-2F. As best seenin FIG. 3A, the first drive system further includes a pair of inneridler pulleys 224 a, 224 b, and a pair of outer pulleys 222 a, 222 bthat, when driven by respective belts 226 a, 226 b, cause the gearedwheel 220 mounted on the same shaft to rotate and thereby propel thevehicle 200 in a vertical direction within a column (along the drivesurfaces of the track). The idler pulleys 224 a and 224 b rotate freelyrelative to the axles and maintain the tension of the belts 226 a and226 b. Each of the outer pulleys 222 a and 222 b is fixed relative tothe axle 215 onto which it is mounted. The first drive system furtherincludes a pair of counter-rotating gears 228 a, 228 b which are rotatedby first onboard motor 230 (FIG. 3B). So driven, belts 226 a and 226 bdrive pulleys 222 a and 222 b, respectively and this rotary motion ofthe pulleys 222 a and 222 b causes rotation of the geared wheels 200mounted on a corresponding shaft 215. Accordingly, when the vehicle 200is moving vertically, the geared wheels 220 carry the weight of thevehicle and any item(s) thereon.

In the embodiments of FIGS. 3A and 3B, the drive axles 215 are rotatablymounted within housing 232 such that their spacing remains fixedrelative to one another. As will be described shortly, the fixed spacingbetween axles 215 in accordance with some embodiments necessitates analignment step with the guiding system (e.g., tracks) before entry of avehicle into the columns which extend between the vertical arrays ofstorage areas 115 (FIG. 1) and within which the guide system is mounted.

In alternate embodiments (not shown), elements of the first drivesystem, as geared wheels 200 and axles 215 may be mounted within housing232 in a manner that allows them to move inwardly so as to relax anyrequirement for precise alignment while also eliminating the risk of anydamage to either the geared wheels 200 or to the guiding system. Inembodiments of the latter type, vehicles intended to carry substantialloads may require motor driven means for temporarily reducing thespacing between axles 215 and thereby accommodate entry of a vehicle 200into the column(s) between storage areas.

With continued reference to FIGS. 3A and 3B, it will be seen that firstmotor 230 is operatively connected with the gears 228 a and 228 b todrive belts 226 a, 226 b and rotate both axles 215 and correspondinggeared wheels 220 in a synchronous manner. The first drive system forthe vehicle 200 is thus configured to synchronously drive the vehicle200 in a vertical direction relative to a track or other guiding system.Specifically, each geared wheel 200 is connected to an end of one of theaxles 215 in a manner that substantially impedes rotation of the gearsrelative to the axle. In this way each axle drives the attached twogears in a synchronous manner. Additionally, in the present instance,both axles are driven in a synchronous manner so that all four gears aredriven in a synchronous manner.

In embodiments, a single drive motor 230 is used to drive both axles. Inthis instance, pulleys 222 a and 222 b serve as timing pulleys rigidlyconnected to the axles 215 to prevent rotation of the pulley relative tothe axle. Similarly, timing pulleys (not shown) are connected to thecounter rotating gears 228 a and 228 b driven by motor 230. In thisinstance, drive belt 226 a connects the timing pulley 222 a with thetiming pulley directly driven, via gear 228 a, by motor 230, while thedrive belt 226 b connects the timing pulley 222 b with the timing pulleyindirectly driven, via gear 228 b, by motor 230. In embodiments, belts226 a and 226 b are each timing belts such that rotation of the drivemotor 230 is precisely linked to the rotation of the axle.

There are various other mechanisms that can be used to synchronouslydrive the axles 215 other than the single-motor arrangement exemplifiedby FIGS. 3A and 3B. For instance, a pair of drive motors can be used todrive the axles, and the drive motors can be synchronized. Inembodiments, the drive motor 230 includes a sensor that is operable todetect the rotation of the motor to thereby determine the distance thevehicle has traveled. Since the gears 200 are rigidly connected with theaxles, which are in turn synchronously connected with the drive motor230, the vertical distance that the vehicle moves can be exactlycontrolled to correlate to the distance that the drive motor 230 isdisplaced. For instance, the sensor 252 may be a sensor such as a hallsensor. The sensor detects the rotation of the motor and sends a signalto a central processor, which determines how far along the designatedpath the vehicle 200 has traveled based on the known informationregarding the path and the rotation that the sensor detects for themotor.

The vehicle may also include an optional transfer mechanism fortransferring items between the vehicle and a destination, such as astorage location.

For instance, the transfer mechanism 210 may be operative to transfer anitem between a platform surface of the vehicle and one of the pluralityof destination areas 810. As shown in FIG. 2A, the platform surface isoptionally defined by the exterior surfaces of a plurality of rollers,indicated generally at 211.

The transfer mechanism 210 may be any of a variety of mechanisms forloading items onto the vehicle and for unloading items from the vehicleinto one of the storage areas. Additionally, the transfer mechanism 210may be specifically tailored for a particular application. In thepresent instance, the transfer mechanism 210 comprises one or moredisplaceable element(s) configured to engage an item stored at a storagelocation and pull the item onto the vehicle. More specifically, in thepresent instance, the vehicle includes one or more displaceableelement(s) configured to move toward a tote in a storage location andreleasably engage the tote. After the displaceable element(s) engage thetote, each displaceable element is displaced away from the storagelocation, thereby pulling the tote onto the vehicle 200.

The displaceable element of the transfer mechanism may any of a varietyof items, such as a bar, rod, or another element configured to engage anitem, for example, a tote. For example, referring to FIGS. 2A, 2B, and2G to 2I, the transfer mechanism 210 may include one or moredisplaceable pins 212 a, 212 b. Additionally, the transfer mechanism mayinclude a drive element for displacing the pins 212 a, 212 b. Forinstance, optionally, the transfer mechanism 210 includes two driveelements in the form of endless carriers such as a drive belt or asshown drive chains 214 a and 214 b. Optionally, each pin 212 a, 212 bprojects or extends inwardly toward the longitudinal center line of thevehicle. The transfer mechanism is preferable configured to cooperateone of the totes to releasably engage the tote. For example, in thepresent instance, the pins 212 a, 212 b are configured to mate with arecess on the tote so that the transfer mechanism can engage the tote.However, it should be recognized that the transfer mechanism may includeany of a variety of elements for engaging items to be transferred ontoof off of the vehicle.

The vehicle includes one or more drive elements for driving the transfermechanism. Optionally, the vehicle includes one or more motors thatdrive the transfer mechanism 210. For instance, one or more motors ofthe vehicle drive system may drive the chains 214 a, 214 b toselectively move the chains and pins 212 a and 212 b toward or away fromstorage locations.

As the vehicle approaches a storage location to retrieve a tote T (FIGS.2G to 2I), the chains may drive the displaceable pins 212 a and 212 btoward the storage location so that the pins underlie a groove or notchin the bottom of the tote. The vehicle travels a small distance upwarduntil the pins 212 a and 212 b (or bar) are disposed with the groove ornotch, as shown in FIG. 2I. The chain then reverses so that the pins 212a, 212 b move away from the storage location 100. Since the pins engagetote T within the notch, as the pins moves away from the storagelocation, the tote is pulled onto a surface of the vehicle. In this way,the transfer mechanism 210 is operable to retrieve items from a storagelocation. Similarly, to store an item in a storage location as location820 in FIG. 7, the chains 214 a, 214 b of the transfer mechanism 210drives the pins 212 toward the storage location until the item is in thestorage location. The vehicle then moves downwardly to disengage thepins from the tote, thereby releasing the tote.

In this instance, and as best seen in FIG. 2H, two or more totes, suchas totes T₁ and T₂, may be coupled and decoupled from one another usingmating connectors indicated generally as 283 a and 283 b, respectively.Optionally, totes T₁ and T₂ may be coupled and decoupled from oneanother through a series of lifting and separating movements implementedby movement of the vehicle 210. Optionally, the transfer mechanism 210may be actuated to pull a forward facing (“lead”) tote onto rollers 211(FIG. 2G) so as to be fully supported by vehicle 200. If the totes arereleasably connected, this pulling motion advances the trailing tote(i.e., the one that is immediately behind the lead tote) into the aislefacing location. Optionally, the first drive mechanism of vehicle 200 isthen operated briefly so that the vehicle 200 travels a verticaldistance sufficient to uncouple the lead tote from the trailing tote(s).Once decoupling is completed, the second drive system may be actuatedagain to center the tote upon the vehicle 200.

The vehicle 200 may include a separate drive element for driving thetransfer mechanism 210. Alternatively, the transfer mechanism may beinterconnected with one of the horizontal or drive elements of thevehicle. Specifically, the transfer mechanism may be connected with oneof the drive systems so that the drive system is selectively operablebetween driving the vehicle and driving the transfer mechanism.

For instance, the transfer mechanism may optionally be connected withone of the horizontal drive systems with a selectable connection so thatin a first orientation the drive system drives the vehicle horizontallyand in the second orientation the drive system drives the transfermechanism. Referring to FIGS. 2C, 3B, and 4A to 4G, there is shown anembodiment of vehicle 200 which further includes an optional clutchmechanism 400 (FIGS. 4B and 4C) that can be engaged (FIG. 4C) anddisengaged (FIG. 4B) to initiate and terminate transmission of power,respectively, from the motor(s) of the horizontal drive system to thetransfer mechanism, whereby the second drive system may be operatedindependently of the transfer mechanism. In this instance, the clutchmechanism 400 may be configured as two clutch sub-assemblies which aresymmetrically arranged relative to a longitudinal centerline of vehicle200, with these sub-assemblies being indicated generally at 400 a and400 b in FIGS. 2C and 3B. In FIGS. 4B and 4C, first clutch sub-assembly400 a is visible and includes a first pivotable carrier 410.Additionally, second clutch sub-assembly 400 b is constructedsubstantially similarly to clutch sub-assembly 400 a and, as such,includes a second pivotable carrier 412 (see FIG. 2C).

As best seen in FIG. 4B, first clutch assembly 400 a includes apivotable carrier, such as first pivotable carrier 410 that is pivotablebetween a first positioned and a second position. The clutch assemblymay include a drive mechanism for actuating the clutch assembly betweenthe first and second positions. Optionally, the carrier 410 may bebiased toward the second position. For example, the pivotable carriermay be biased toward the second position and the biasing element may beconfigured so that the weight of the vehicle is sufficient to overcomethe bias of the biasing element to pivot the carrier 410 to the firstposition. Specifically, the carrier 410 may be maintained in a firstangular orientation relative to an underlying support surface S whilethe full weight of vehicle 200 is distributed among wheels 254 a, 254 b,256 a, 256 b, 252 a and 252 b. FIG. 4C illustrates the vehicle in araised position in which the weight of the vehicle is released so thatthe biasing element biases the clutch toward the second position.Specifically, as the vehicle 200 moves vertically in a direction awayfrom underlying surface S, pivotable carrier 410, 412 are urged by acompressed coil spring 414 into the second angular position, which isreached when vehicle 200 has reached an elevation above surface S thatis of at least dimension g₁ shown in FIG. 4C. Referring to FIG. 4B, itwill be seen that a first transfer drive element 280 is rotatablycoupled to the first pivotable carrier 412 and that a first endless loopelement 284 transfers rotary power to the first drive element 280. Theendless loop element may be any of a variety of power transfer elements,such as a chain or a belt. In this instance, the endless loop elements284 is a belt.

Driven element 280 may be a pulley or a gear driven by the second motorof vehicle 200. Likewise, sub-assembly 400 a may be driven by the thirdmotor of vehicle 200. In this instance, the first transfer element 280is dimensioned and arranged to engage the first endless loop element 280to drive the first driven elements whenever the drive motor 250 b isrotated. That is, regardless of whether clutch mechanism sub-assemblies400 a and 400 b are engaged to drive the transfer mechanism, the firstand second driven elements 270, 280 will rotate with the second andthird motors 250 a, 250 b, respectively.

As noted previously, and in accordance with one or more embodimentsconsistent with the present disclosure, the second and third motors arecoupled to engage the transfer mechanism when the vehicle has beenelevated, relative to an underlying support surface S, by dimension H(FIG. 4C). Such elevation causes the pivotable carrier 410 to pivot outof the first angular orientation shown in FIG. 4B and into the secondangular orientation shown in FIG. 4C. In the first position shown inFIG. 4B, transfer element 280 is spaced apart from drive element 282.Drive element 282 is connected with the transfer mechanism 210 toprovide the driving power to drive transfer mechanism 210. In the firstposition in which transfer element 280 is spaced apart from driveelement 282, the drive element for transfer mechanism 210 isdisconnected from the drive motor 250. In the second position shown inFIG. 4C, the transfer gear 280 is pivoted into engagement with the driveelement 282 so that the drive element for the transfer mechanism isconnected with the drive motor.

As shown in FIGS. 4A to 4C, when the clutch 400 a,b pivots from a firstposition to a second position, the drive element for the transfermechanism 210 a,b is connected with the drive motor 250 a,b, whichcauses rotation of first sprocket 290 a, 290 b which, in turn causesfirst and second chains 214 a, 214 b to move pin 212 a (FIG. 4A) and pin212 b (FIG. 4B) toward or away from a container to be transferred to orfrom vehicle 200. When the wheels of vehicle 200 once again rest uponthe surface S, as depicted in FIG. 4B, the drive elements 282 is againdecoupled. As such, continued operation of the second and third motorsof the vehicles as to propel vehicle 200 upon surface S, ceases to haveany effect on the transfer mechanism 210.

In some applications, it may be desirable for vehicle 200 to beconfigured to load and unload items that differ from the totes describedabove. For example, it may be desirable to configure the vehicle so thatit is operable to load and unload any of a variety of boxes, cartons,trays and the like, or any combination of these, and they may containone or a plurality of items of inventory. In one or embodiments, suchitems are accommodated by a transfer mechanism 210 which incorporate analternative or additional discharge assistant. With particular referenceto FIGS. 2G and 4A to 4D, it will be seen that rotation of sprocket 290causes chains 214 a, 214 b to drive sprockets 217, wherein each of thedriven sprockets causes rotation of a corresponding one of the rollers,as rollers 211 (FIG. 2G). The direction in which the pairs of sprockets217 are rotated determines whether the rollers of transfer mechanism 210are operated to assist in loading or in unloading of an item,

FIGS. 4D and 4E are side elevation views of the exemplary automatedguided vehicle 200 of FIGS. 2A-2F, the lateral exterior cover platebeing omitted to reveal an optional actuator mechanism 400 having aforce imparting member 402 which is selectively movable between a firstposition (FIG. 4D) and a second position (FIG. 4E). FIG. 4F is anenlarged view of the actuator mechanism 400 depicted in FIGS. 4D and 4E,the force imparting member 402 being shown in the first, non-forceimparting position. FIG. 4G is an enlarged view of the actuatormechanism depicted in FIGS. 4D to 4F, the force imparting 402 thereofbeing shown in the second, force imparting position.

As noted previously in the discussion of FIG. 4F, the wheels 220 aremounted onto two parallel spaced apart axles, as axle 215 depicted inFIG. 2F, so that two of the wheels are disposed along the forward edgeof the vehicle and two of the wheels are disposed along the rearwardedge of the vehicle. In one or more embodiments, the optional actuatormechanism 400 includes a threaded portion 404 of each axle 215 and arespective pair of carriers 406. Each respective carrier 406 has acorrespondingly threaded bore dimensioned and arranged to receive thethreaded portion 404 of an axle 215 and carries one of a pair of forceimparting members 402. In one or more embodiments, the force impartingmembers are rollers which are freely rotatable within carriers 406 aboutaxes of rotation which are transverse to the axes defined by axles 215.

Force imparting members 402 may be selectively actuatable without theneed for a dedicated motor to drive the force imparting member.Optionally, rotation of motor 230 (FIG. 3B) causes axles 215 to rotate,which drives carriers 406 forwardly until they encounter a stopwhereupon continuation of the axles 215 produces no further movement ofthe carriers 406. When positioned as shown in FIG. 4G, each forceimparting members exerts a normal force upon a surface of one of thewheels as, for example, while the wheels 252 a, 252 b are being drivenby the second and third motors, respectively. Such actuation of theforce imparting members 402 increases frictional contact of wheels 252 aand 252 b and thereby provides better directional control as the vehicle200 is moved across underlying surface S (FIG. 4G). As the wheels 252 a,252 b are only required while the vehicle is external to the array ofstorage area 215, motor 230 and axles 215 are able to serve a dualpurpose.

Thus, with continuing reference to FIGS. 3B and 4D to 4G, it will beseen that in some embodiments, vehicle 200 includes a first pair ofmotor driven omnidirectional rollers and a second pair of motor drivenomnidirectional rollers, wherein a first omnidirectional roller of eachpair is dimensioned and arranged to rotate about a first axis ofrotation, wherein a second omnidirectional roller of each pair is drivenfor rotation about a second axis of rotation, a fifth roller driven byone of the first motor and the second motor; and an actuator movablefrom a first position to a second position to selectively urge the fifthroller in a direction toward an underlying support surface; wherein asurface of each of the first and second pairs of omnidirectionalrollers, and a surface of the fifth roller are dimensioned and arrangedto contact the underlying support surface while the actuator ismaintained in the first position, and wherein movement of the actuatorinto the second position causes a transfer of load from one or more ofthe omnidirectional rollers to the fifth roller.

In one or more embodiments, the vehicle 200 may be powered by anexternal power supply 95, such as a contact along a continuous chargingrail or, alternatively, using an inductive power transfer coil, eitherof which serving to provide the electric power needed to drive thevehicle. However, in the present instance, the vehicle 200 includes anonboard power source that provides the requisite power for both thefirst drive motor 230 and the motors that drive the second drive system.The onboard power supply may be rechargeable. In that regard, the powersupply may include a power source, such as a rechargeable battery, abank of ultra-capacitors, as capacitors 240 (FIG. 3B) or a combinationof these. For example, ultra-capacitors can accept very high amperage ina recharging operation. By using a high current, the ultra-capacitorscan be recharged in a relatively very short period of time, measurablein seconds or minutes as compared to the hours which may be required tocharge a suitable battery. On the other hand, provisions can be made,according to one or more embodiments, to automate the process ofreplacing a discharged battery, with a recharged one, as part of theprocess of operating one or more of the vehicles.

Where a charging rail is used, each vehicle 200 may include one or morecontacts for recharging the power source. In the present instance, thevehicle may include a plurality of brushes, such as copper brushes thatare spring-loaded so that the brushes are biased outwardly. The brushescooperate with a charging rail to recharge the power source, asdescribed further below. For instance, a pair of charging rails may bedisposed along the columns within which the vehicles 200 move during asequence of one or more storage and/or retrieval tasks. Alternatively,vertical and/or horizontal charging rails may be arranged withincharging stations disposed in the vicinity of the workstation 500 (FIG.7).

Optionally, the charging rails are conductive strips connected with anelectrical supply. The charging contacts of the vehicle 200 engage theconductive strips to recharge the ultra-capacitors. Specifically, thebiasing element of the brushes biases the brushes outwardly toward thecharging contacts. The electricity flowing through the charging contactprovides a high amperage, low voltage source that allows theultra-capacitors to recharge in an interval measurable in seconds orminutes, depending upon the amount of power consumed during a sequenceof inventory management tasks or subtasks.

Vehicles utilizing ultra-capacitors as a power source may rechargecharges each time the vehicles travel within a loading column and/orutilize a charging station disposed along a path taken in the course ofperforming an inventory management tasks.

Optionally, each vehicle may include one or more load sensors fordetecting that an item is loaded onto the vehicle. The sensor(s) ensurethat the item is properly positioned on the vehicle. For instance, theload sensor may include a force detector detecting a weight change or aninfrared sensor detecting the position of an item on the vehicle.

The vehicle 200 may be semi-autonomous or, alternatively, fullyautonomous. In the latter regard, a multitude of non-contact systemshave been proposed for the purpose of continuously determining theactual position of an automated guided vehicle in absolute coordinates,and resetting navigational parameters (i.e., X, Y, and heading) to nullout accumulated errors, thereby re-referencing the vehicle. Any of thesemay be utilized in the implementation of position referencing forautomated guided vehicles in an inventory management system consistentwith embodiments of the present disclosure. Such referencing systems canbe ultrasonic, RF, or optical in nature, with ultrasonic and opticalbeing especially suited to indoor scenarios. Of these latter twocategories, optical systems are generally more accurate and thereforemore widely employed in commercial practice.

Exemplary position sensing systems utilize a scanning mechanism thatoperates in conjunction with fixed-location references strategicallyplaced at pre-defined surveyed sites. Such scanning mechanisms mayinclude scanning detectors with fixed active-beacon emitters, scanningemitter/detectors with passive retroreflective targets, scanningemitter/detectors with active transponder targets, and rotating emitterswith fixed detector targets.

In one or more illustrative embodiments consistent with the presentdisclosure, the vehicles may optionally rely on a scanning lasertriangulation scheme (SLTS) to provide positional updates to an onboarddead-reckoning system of the vehicle. A laser emitter rotating at, forexample, two rpm illuminates passive retroreflective barcode targetsaffixed to walls or support columns at known locations on the order offifteen meters away from the vehicle. The barcodes are used topositively identify the reference target and eliminate ambiguities dueto false returns from other specular surfaces within the operating area.An onboard computer of each vehicle calculates X-Y positional updatesthrough simple triangulation to null out accumulated dead-reckoningerrors.

Alternatively, each vehicle 200 may optionally utilize retroreflectivetargets, distributed throughout the operating area, in a manner whichallows both range and angular orientation to be determined by eachvehicle. For example, a servo-controlled rotating mirror on the vehiclemay optionally pans a near-infrared laser beam through a horizontal arcof 90 degrees at, for example, a 20-Hz update rate. When the beam sweepsacross a target of known dimensions, a return signal of finite durationis sensed by the detector. Where the retroreflective targets are all thesame size, the signal generated by a close target will be of longerduration than that from a distant one. Angle measurement is initiatedwhen the scanner begins its sweep from right to left, where detection ofthe reflected signal terminates the timing sequence.

As yet another position reference technique which may be employed in thevehicle is a laser-based scanning beacon system computes vehicleposition and heading using cooperative electronic transponders withpassive reflectors. Such a scanner mechanism includes a rotating mirrorattached at, for example, a 45-degree angle to the vertical shaft of anincremental optical encoder. To improve azimuthal accuracy, optionally atimer interpolates between encoder counts. The fan-shaped beam divergesvertically at, for example, a four-degree spread angle, to ensure targetdetection at long range while traversing irregular floor surfaces. Eachtarget is uniquely coded, and many (e.g., 32) targets can be processedin a single Scan, with vehicle X-Y position calculated every 100milliseconds.

In one or more embodiment, each vehicle may maintain, in memory, aninternally stored map of its own position within a facility. Inaddition, each vehicle provides signals to the central controller thatmay include data such as position, speed, angular orientation in theplane of travel, and a selected path of travel data to other vehicles inthe facility. The vehicle may also include a receiver so that thevehicle can receive such data regarding other vehicles. The vehicle mayreceive such data regarding other vehicle either directly from othervehicles or from a central controller. Using the vehicle data, eachvehicle may maintain a dynamically updated map which reflects theposition of all vehicles in the particular zone(s) of an inventorymanagement facility to which that vehicle has been assigned. Whendynamically updated position data is available locally at each vehicle,a task may be assigned to a vehicle by a central controller 450,including the path segments taken by a vehicle to reach the location(s)where elements of the assigned task are to be performed may be selectedby the vehicle.

Each vehicle may include a processor configured to execute steps of anavigation process stored in memory which cause the vehicle to follow ashortest path from a current location of the vehicle to a destinationwhere the next subtask(s) of an assigned task are to be performed. Insuch embodiments, the central controller 450 need not be configured toexecute traffic control and collision avoidance functions (unless abackup control scheme is desired) but, instead, the central controller450 may be configured to transmit signals representative of instructionswhich identify the next task(s) to be assigned to each vehicle and whichspecify the various locations within the facility where those tasks areto be performed. The vehicles, on the other hand, may be configured totransmit signals to the controller which are representative of taskassignment acknowledgements, position updates, status updates (e.g.,sub-task completed or in process, current power status, etc.), and otherinformation which the controller may require to assess the relativeability of the vehicles to perform tasks awaiting assignment.

In a fully autonomous scheme according to one or more embodiments, eachvehicle may alternatively utilize a local processor to determine speedand direction of movement from sensed indicia placed on an underlyingsupport surface in one or more zones of an inventory managementfacility, to exchange that positional data with other vehicles withinthe facility, and to maintain a dynamically updated, local map toachieve a form of decentralized traffic control in manner similar tothat described above using other positional sensing approaches.

In semi-autonomous configurations of vehicles 200, also referred to asautomatic guided vehicles (AGVs), a central controller, such ascontroller 450, provides traffic control functions needed, for example,to prevent collisions of the vehicles with one another and/or with anypotential obstructions to vehicle movement which may be present in theone or more zone(s) of a facility to which a subset of vehicles areassigned. In such embodiments, the controller 450 receives currentposition and bearing data in the form of update signals transmitted fromthe vehicles 200. The received position and bearing data are comparedwith estimates that the controller has derived from prior speed andheading instructions transmitted by the controller to the vehicle. Basedon the comparison, the controller 450 may determine that corrections toone or more of the velocity and the direction of one or more vehiclesthat is needed to prevent a collision and, if so, transmit thoseinstructions to the vehicle(s).

In one or more semi-autonomous embodiments, each vehicle 200 may includea reader for reading indicia placed on a surface upon which the vehicleis traveling and/or in positions within access columns aligned with thearray of storage areas 115 (FIG. 1C). In some embodiments, each indiciumof a first group of indicia corresponds to a unique location to form agrid of locations. These locations may be stored in a data table in amemory accessible to a processor of the vehicle, of the centralcontroller 450, or a both. By following a path designed to intersectwith a particular sequence of these indicia, each vehicle may transmitan identifier of an indicium as it passes over it and confirm it tocontroller 450 whereupon a semi-autonomous guiding of the vehicle isachieved via instructions transmitted by the controller to the vehicle.From this information and other data reported by each vehicle,controller 450 can confirm the speed, direction, and path of movementfor each vehicle. In one or more embodiments, controller 450 utilizesspeed and directional data to enforce collision avoidance policies, toassign inventory management tasks according to the location and powerreserve status of each vehicle and, in the interest of safety, tomaintain an appropriate distance from any personnel permitted in thearea.

Additional indicia may be affixed, within the access columns or tostored totes themselves, at positions adjacent to each storagelocations. Here, each indicium may bear include a unique bar code, andthe reader on each vehicle 200 may scan the area around the storagelocation at which an item is to be delivered or retrieved. The data thatthe central processor 450 has regarding the path that a vehicle 200 hasto follow and the data regarding the distance the vehicle has traveledbased on the data regarding the rotation of the drive motor may besufficient to determine whether the vehicle 200 is positioned at theappropriate storage location within the storage areas. Nonetheless,indicia adjacent the storage areas permits a redundancy check of thelocation of the vehicle before an item is discharged into or receivedfrom the appropriate storage location. Therefore, the scanner mayoperate to scan and read information regarding the storage location atwhich the vehicle is stopped. If the scanned data indicates that thestorage location is the appropriate storage location, then the vehicledischarges its item into the storage location. Similarly, the vehiclemay have a second reader for reading indicia adjacent the rearward edgeof the vehicle. The second reader may be used in applications in whichthe system is set up to utilize a first series of storage locationsalong the forward side of an access column and a second series ofstorage locations along the rearward side of an access column, as shownin FIG. 1.

In some embodiments, functionality for autonomous or semi-autonomousguidance of the vehicles 200 may be integrated into one or morefunctional accessory. Such an approach may be beneficial where preciseposition sensing is required in some zones within an inventorymanagement facility, but a less precise position sensing approach may beacceptable in other zones. For example, in embodiments such as thatdepicted in FIG. 1, functional accessories 700 are depicted as serving asupporting role to maintain a necessary supply of items to operators ata workstation.

In the foregoing description, the vehicles have a vertical drive 220that is dimensioned and arranged to interact with tracks disposedadjacent storage areas 820 of racks 800 as discussed further below. Thedrive gears effect the raising or lowering of a vehicle, depending uponthe direct of rotation of motor 230. As well, the functional accessoriesmay incorporate tracks that cooperate with the vertical drive so as topermit a vehicle to raise and lower a functional accessory with which itis associated.

In some embodiments, the processor of each vehicle controls theoperation of the vehicle in response to signals received from thecentral processor 450. Additionally, the vehicle includes a wirelesstransceiver so that the vehicle can continuously communicate with thecentral processor as it travels along the track. Alternatively, in someapplications, it may be desirable to incorporate a plurality of sensorsor indicators along paths which the vehicles may traverse. The vehiclemay include a reader for sensing the sensor signals and/or theindicators, as well as a central processor for controlling the operationof the vehicle in response to the sensors or indicators.

As shown in FIG. 1, a material handling system 10 may include a numberof different stations or areas. For instance, the system 10 may includea large number of storage locations arranged in numerous racks 800. Theracks may accommodate thousands or tens of thousands of storagelocations. Additionally, the system may optionally include smaller racksreferred to as flow racks 600, which are designed to accommodate highervolume fast moving items. These flow racks 600 may positioned nearworkstations WS so that operators at the workstation may readily accessthe items. The vehicles may be adapted to operate in of differentaspects of the system, including but not limited to the flow racks 60and the storage racks 800.

MOVEABLE TRACK

At a location proximate a workstation, one or more flow rack structures600 can supply the workstation operator(s) with items of inventory whichare required or expected to be required based on a demand forecast, tofulfill inventory management requests in an upcoming inventorymanagement interval (e.g., to satisfy e-commerce or mail orders duringone or more upcoming picking cycles).

Referring to FIGS. 1 and 6A-6F The vehicles 200 may optionally beoperable to supply items to a variety of flow rack structures 600. Theflow rack 600 may include a plurality of storage locations for receivinga plurality of items, such as totes 55 or other containers. The storagelocations may be arranged in a plurality of columns 605. Each columnoptionally includes a plurality of vertical rails 610 that support aplurality of horizontal support elements that support the totes 55. Forinstance, the vertical rails may support a plurality of generallyhorizontal shelves 612 vertically spaced apart from one another. Thespacing between the shelves may vary to provide storage locations havingdifferent heights within the same column.

The storage locations may be generally horizontal locations.Alternatively, the storage locations may be angled relative to thehorizon so that items in the storage locations 612 tend to move towardthe front edge of the storage location as shown in FIG. 6B. An elementsuch as a vertical lip or a flange may form a stop impeding the itemfrom sliding off the front edge of the storage location.

The backside 615 of the flow rack is generally open so that the verticalrails frame an opening into each storage location (i.e. tier or shelf612). The opening provides access for transferring a supply of itemsbetween the flow rack 600 and a delivery system. For instance, totes maybe delivered to the flow rack 600 and an operator may lift the totesonto the shelves through the backside of the flow rack.

The storage locations 612 may be large enough to accommodate a pluralityof tote. Specifically, each storage location may have a length that isgreater than the length of a plurality of totes so that a number oftotes can be fed into the storage location to form an aligned series oftotes. As the operator empties the tote closest to the front of thestorage location, the tote is removed and the tote behind the empty toteslides forward or is conveyed forward to the font of the storagelocation.

In some applications, it may be desirable to deliver the totes directlyto the flow racks using the vehicles 200. Accordingly, the system mayinclude an option track that the vehicles can climb to raise the vehicleinto alignment with the appropriate storage location so that the vehiclecan transfer the tote to the storage location 612 in the flow rack 600.

Referring to FIGS. 5A-5F an optional structure configured to cooperatewith the vehicles 200 to raise the vehicles is designated generally 700.The structure may be a lift such as an elevator that includes a poweredelement for lifting the vehicle. Alternatively, the structure mayinclude a guide or track configured to cooperate with the vehicle toraise the vehicle without an externally powered mechanism. For instance,the structure 600 may include a track 620 configured to cooperate withthe vertical drive 220 of the vehicle. The vehicles may drive up thetrack 620 to lift the totes 55 to the desired storage location 612 inthe flow rack.

Optionally, the structure 700 is moveable so that the structure can bemoved to different columns 1105 in the flow rack. Additionally,optionally, the structure 700 in configured to cooperate with thevehicle so the vehicle can move the structure 700 to the desiredlocation. Further still, optionally, the structure 700 is configured tocooperate with the vehicle 100 so that the vehicle can lift thestructure vertically and convey the structure horizontally along a pathtoward a storage location, such as along a path toward one of thecolumns of the flow rack. In this way, the structure 700 optionallyincludes a track 720 that the vehicle can climb. The vehicle may also beoptionally configured to move the track vertically or horizontally to adesired location and then climb the track.

Referring to FIGS. 5A-5B, an optional structure providing a moveabletrack 700 is illustrated. The moveable track includes a supportstructure forming a vertical column. The column includes a plurality ofspaced apart vertical posts 710 a,b,c,d. The posts are generallyparallel to one another and spaced apart to form a column having alength and width corresponding to the length and width of the vehicle.In particular, the vertical posts are spaced apart so that post 710 aand 710 b form an opening at least as wide as the width of the vehicle.Post 710 c is parallel to post 710 a and spaced apart from post 710 a adistance at least as long as the approximate length of the vehicle. Post710 d is parallel to post 710 b and 710 c and together with post 710 cforms an opening that forms a discharge opening for transferring itemsbetween the vehicle and a storage location. The moveable column 700 mayinclude a plurality of horizontal rails 712 interconnecting the posts710 a-d and or cross brackets connecting the posts to form afree-standing structure.

The moveable column 700 may also include a structure that cooperateswith the vertical drive 220 of the vehicle so that the vehicle can climbupwardly. For instance, the moveable column may include one or moretrack elements configured to cooperate with the vehicle to allow thevehicle to climb upwardly. Optionally, the track elements may include aplurality of teeth vertically spaced apart along the track. The trackmay have teeth spaced at a uniform pitch to cooperate with the climbinggears 220 of the vehicle. Although the track 720 is described as havinga plurality of teeth, it should be understood that the track can be anyof a variety of structures configured to permit the vehicle to climbupwardly. Accordingly, the term track may mean any guide configured tocooperate with the track to facilitate the vertical displacement of thevehicle.

The track 720 may be connected with the structure 700 in a variety oforientations depending upon the configuration of the vertical drive ofthe vehicle. In the present instance, the track is oriented to cooperatewith the vertical drive gears 220 of the vehicle. Optionally, the trackis connected with the structure 700 to cooperate with the vehicle sothat the vehicle can climb vertically while maintaining the orientationof the vehicle relative to the horizon. In other words, the track may beconnected with the structure so that the vehicle can climb the trackwithout tilting relative to the horizon.

For instance, a first track element 720 a may be mounted on the insideof post 710 a and a second track element 720 b may be mounted on theinside of post 710 b. The two tracks 720 a,b may be spaced apart adistance corresponding to the distance between the drive gears 220 ofthe vehicle. Similarly, a third and fourth track may be mounted on theinside of posts 710 c and 710 d and spaced apart a distancecorresponding to the distance between the drive gears. Accordingly, thevertical drive gears 220 of the vehicle may be driven synchronously sothat the vehicle may climb the tracks while maintaining the horizontalorientation to keep the vehicle from tipping relative to the horizon.

Referring to FIGS. 5A-5C, the moveable track 700 is shown with thevehicle 100 in a lowered position so that the vehicle is on a horizontalsurface, such as the floor. The moveable track may be resting on thesame horizontal surface as the vehicle. In FIGS. 5D-5E the moveabletrack is shown in a raised position in which the vehicle has lifted thetrack. Specifically, when the vehicle 200 is positioned within thecolumn, activating the vertical drive 220 in a first direction causesthe vertical drive 220 to drive the track upwardly, thereby lifting themoveable track 700. Once the vehicle raises the moveable track, thehorizontal drive 252, 254, 256 are operable to displace the vehiclehorizontally to move the moveable track horizontally.

Additionally, when the vehicle 200 is positioned within the column,driving the vertical drive 220 in a second direction causes the vehicleto lower the moveable track if the track is raised. Alternatively, ifthe moveable track is supported on the floor or similar horizontalsurface, driving the vertical drive 220 in a second direction causes thevehicle to drive upward along the track. Similarly, if the vehicle is inthe track above the ground, driving the vertical drive in the firstdirection causes the vehicle to drive vertically downwardly until thevehicle reaches the ground.

The vertical drive 220 of the vehicle may be configured so that thevertical drive gears 220 are displaceable inwardly to reduce thedistance between the vertical drive gears. In this way, the drive gearscan be moved inwardly to provide clearance between the tracks 720 andthe vertical drive gears as the vehicle drives into the column.Alternatively, as described above, the vertical drive gears may bemounted on shafts so that the axis of rotation of each vertical gear issubstantially parallel to the horizontal direction of travel.Additionally, the axes of rotation of the vertical drive gears may besubstantially fixed so that the lateral distance between each pair ofvertical drive gears is substantially fixed. Therefore, in order toenter the column, the teeth of the vertical drive teeth are aligned withthe teeth in the track 720 so that the teeth of the vertical drive gearspass through the teeth in the track.

Referring to FIG. 5C, the track 720 and the vertical drive gear 220 maybe aligned so that the vertical drive gears do not impinge upon orcontact the track when the vertical gear is translated relative to thetrack. For instance, the spacing between the teeth of track 720 providessufficient clearance for the teeth of the vertical drive gear 220 topass between the gaps between the teeth of track 720 when the verticaldrive gear translates horizontally along a line that is parallel to theaxis of rotation of the vertical drive gear 220. More specifically, thevertical drive gear and the track may be configured and positioned sothat the addendum circle of the vertical drive gear 220 overlaps withthe addendum line of the teeth in the track. While the addendum circleof the drive gear overlaps the addendum line of the track, the teeth ofthe gear are configured and oriented so that the vertical drive gearpasses through the gaps between teeth in the track 720.

Referring again to FIG. 5C, optionally, the vertical drive gear 220 andthe track 720 may be configured and oriented to increase the clearancefor the vertical drive gear to pass through the track when the vehicledrives into the moveable track 700 (i.e. when the vertical drive geartranslates so that the axis of rotation of the vertical drive geartranslates horizontally into the moveable track). For instance, thetrack 720 may have an upper portion and a lower portion 725. The upperportion may have a tooth pitch and configuration to mate with the teethof the vertical drive gear 220. The lower portion 725 may have a toothpitch that is substantially similar to the tooth pitch of the uppersection, but the tooth profile of the lower section may be substantiallydifferent than the upper section. For instance, the teeth of the lowersection may be substantially narrower than the teeth of the uppersection. For instance, the teeth may be at least 10% narrower andpreferably at least 20% narrower. Optionally or additionally, the teethof the lower section 725 may have dedendum that is substantially greaterthan the dedendum of the upper section. For instance, the dedendum ofthe lower section may be greater than the upper section so that the rootof the teeth extends inwardly away from the drive gears a greaterdistance than the root of the teeth of the upper section. For instance,the dedendum of the teeth of the lower section may be 10% greater andpreferably is 20% greater.

Additionally, the lower section may optionally have a tapered pitch lineso that the clearance between adjacent teeth gradually diminishes as theteeth progress up the height of the lower section. In other words, theclearance 728 between adjacent teeth at the bottom of the lower sectionis greatest and the spacing between adjacent teeth at the upper part ofthe lower section is at a minimum and the clearance gradually decreasesfrom the maximum to the minimum.

Configured as described above, the vertical drive 220 may optionally beconfigured to pass through openings in the track so that the verticaldrive is aligned with the track. After the vertical drive is alignedwith the track, the vertical drive is positioned to cooperate with thetrack to raise the track and/or to climb the track as described furtherabove.

The moveable column 700 may be used in conjunction with other elementsof the system 10. For instance, as mentioned above, the system mayoptionally include racks of storage locations, such as flow racks 600.It may be desirable to connect the moveable track with another portionof the system, such as the optional flow rack 600. Accordingly, it maybe desirable to provide a connector on the moveable track 700 that isconfigured to releasably engage the flow rack 600 or other elements towhich the track is to be releasably connected.

As shown in FIG. 6B, the moveable track 700 may incorporate connector727 that releasably connects the moveable track with the flow rack 600.Optionally, the flow rack may include a mating connector, such asconnector 627 that matingly engages the connector 727 on the moveablerack. The connectors 727, 627 may be any of a variety of mechanicalconnectors. In the present instance, the connectors 727, 627 areconfigured so that relative vertical displacement of the column relativeto the flow rack connects the two connectors. Optionally, relativevertical displacement of the column relative to the flow rack in thereverse direction releases the two connectors. Additionally, themoveable track 700 may include a series of connectors 727 a, 727 b thatcooperate with a plurality of connectors 627 a, 627 b attached to theflow rack 600. In this way, one or more connectors optionallyinterconnect the moveable track 700 with the flow rack to impede lateraldisplacement of the moveable track relative to another item of thesystem, such as the flow rack 600.

Configured as discussed above, the system may optionally include amoveable track 700 that cooperates with a portion of the system, such asa flow rack to enable the vehicle to deliver an item to a raised storagelocation. Specifically, the vehicle 200 may be controlled by acontroller, such as a central controller to guide the vehicle intoalignment with an opening configured to receive the vehicle. Optionally,the moveable track comprises a moveable column and the vehicle isaligned with an opening into the interior of the column. The vehicle maythen drive through the opening and into the column. The vehicle 200 maybe driven into alignment with a track 720 in the column so that a drivemechanism of the vehicle engages the track. For instance, optionally,the vehicle includes a vertical drive mechanism 220 that cooperates withthe track 720.

Once vertical drive 220 is aligned with the track 720, the system maycontrol the vertical drive to drive the vertical drive in a firstdirection that operates to raise or lift the moveable track 700 abovethe surface that supports the vehicle. Once the track is lifted, thevehicle 200 may be driven in a horizontal direction to move the moveabletrack to an alternate location. Optionally, a horizontal drive system252 of the vehicle is controlled to drive the vehicle. For instance, thevehicle may be driven toward a structure such as a flow rack so that anopening of the moveable column is aligned with an opening of the flowrack. Additionally, the vehicle may be displaced horizontally so thatconnectors 727 of the moveable column are aligned with connectors 627connected to the flow rack 600. Once the connectors are aligned, drivingthe vertical drive of the vehicle in a second direction operates tolower the moveable rack vertically downwardly. Optionally, driving thevertical drive in a second direction lowers the connector(s) 727 ofmoveable track into engagement with the connectors of the flow rack toreleasably connect the moveable track with the flow rack.

In addition to moving the moveable rack 700, optionally the vehicle 200is configured to climb the rack. For instance, the moveable rack mayinclude a track 720 that extends vertically upwardly and once the rackis positioned on the ground adjacent the flow rack, driving the verticaldrive 220 in the second direction operates to drive the vehiclevertically up the track 720. As shown in FIG. 6D, the vehicle may drivevertically upwardly until the vehicle is aligned with an opening in thecolumn and an opening in the back of the flow rack and a storagelocation 612, such as a shelf, of the flow rack. Once aligned with theshelf, the vehicle may transfer an item, such as a tote onto the storagelocation of the flow rack. Alternatively, the vehicle may transfer anitem from the storage location onto the vehicle. In this way, thevehicle is operable to move a moveable rack, climb the rack and transferan item between the vehicle and a storage location.

As described above, the vehicle is operable to move a moveable track 700and connect the track with a storage mechanism, such as a flow rack.After connecting the moveable track to the flow rack, the vehicle maydrive out of the column leaving the moveable rack in alignment with andconnected to the flow rack. After the vehicle exits the moveable columna second vehicle may enter the column while the column remains connectedwith the flow rack. The second vehicle may then climb the track 720 todeliver an item to one of the storage locations and/or to remove an itemfrom a storage location. For example, the second vehicle may driveupwardly into alignment with storage location 612 b and actuate atransfer mechanism 210 to transfer an item through an opening in thecolumn and into the storage location. The vehicle may then movevertically along the track to align the vehicle with storage location612 a and actuate a transfer mechanism to transfer an item from storagelocation 612 a onto the vehicle. The vehicle may then drive downwardlyand then out of the column to deliver the item to another area, such asto another storage location or to an operator.

As shown in FIG. 6A, the vehicle 200 may be controlled to selectivelyalign the moveable column 700 with one of a plurality of columns in aseparate storage system. For instance, the storage system, such as flowrack 600 may include a plurality of columns. The system may identifywhich of the columns the moveable column is to cooperate, and thecontroller may then direct the vehicle to drive the rack to theidentified column.

Some flow rack structures may feed articles to a workstation usingunpowered rollers for single direction feeding assisted solely by theforce of gravity. Alternatively, and as shown in FIG. 6D, rack structure600 may utilize a bidirectional network of parallel belts 628 or otherconveying element in order advance items toward or away from the pickstation. Driving one or more of belts 628 in a first direction conveysthe articles away from the vehicle and toward the pick station(s).Alternatively, driving the belt(s) in a second direction that is reversethe first direction conveys the articles toward the vehicles.

Turning now to FIG. 6C, there is shown a side elevation of theillustrative embodiment of FIGS. 6A and 6B, subsequent to docking of themoveable rack 700 with the flow rack structure 600 and elevation of thevehicle 200 within the task activity zone Z. As depicted, theillustrative rack structure includes three tiers of storage locations,indicated generally 612 a,b,c, respectively. The vehicle 200 is shown ashaving reached a vertical elevation within task activity zone Z ofcolumn 700 that is aligned with the uppermost storage tier 612 c, andthe rollers of the vehicle transfer mechanism 210 have already beenactivated to advance container C onto a target surface of rack structure600.

In one or more other embodiments of inventory management system 600,vehicle 200 may incorporate the clutch mechanism-equipped second drivesystem and transfer mechanism features of vehicle 200. In suchembodiments, an onboard motor of vehicle 200 is operated to cause thevehicle to climb within activity zone Z. In the present instance, gearwheels of vehicle 200 rotate against teeth of track 720. As a result,forward omnidirectional wheels and rear omnidirectional wheels leavetheir respective positions of support upon the underlying supportsurface. In addition, pivotable carriers drop the second drive elementsand, at the same time, one or more clutch mechanism(s) are engaged.Engagement of the clutch mechanism(s), in turn, enables rotation of thesprockets of the transfer mechanism 210. Rotation of one or moreadditional motors drives endless carrier and cause the transfermechanism to advance the container C onto surface 612 c of the storagestructure 600.

With continuing reference to FIG. 6C, it should be noted that if thepitch angle of the storage tiers is sufficient, it may be possible forcontainers C to advance solely by action of gravity in for example, apassive roller or a chute configuration. In the embodiments exemplifiedby FIGS. 6D to 6G, however, the multi-level rack structure(s) 600 ofinventory management system 600 includes a discharge assistant at eachlevel. In some embodiments the discharge assistant comprises a pluralityof parallel belts 628 and, optionally, sensors for determining thetiming for advancing inventory items deposited by vehicles, as vehicle200, toward the end closest the picker(s).

By way of illustrative example, inventory management system 600 isdeployed in an order fulfillment facility according to an e-commerceapplication. Vehicle 200 supplies containers, as containers C1 and C2which may contain a plurality of individual inventory items. In thisinstance, a warehouse management system (WMS) of the facility hasdetermined that subsets of inventory items, indicated generally atI_(S1), I_(S2), I_(S3), I_(S4), I_(S5), and I_(S6), will be needed atsufficient volumes during the current or an approaching inventorymanagement interval as to justify their continued placement in rackstructure 600. In embodiments, dynamic placement of inventory itemsutilizing vehicles 200 and moveable tracks 700 reduces the time neededto retrieve items so that they can be packaged for shipment as part ofan e-commerce operation. By way of illustrative example, a humanoperator moves between a packing station and the item transfer area Aproximate rack structure 600, which isolates them from vehicle 200operating in item transfer area B.

With reference to FIGS. 6D and 6E, it will be seem that vehicle 200 hasdiscontinued its ascent within the task management zone of the moveablerack 700, having stopped at the transfer position associated with aplurality of third tier locations indicated generally as 612 c at whichare also collectively identified at numeral 606 in FIG. 6D and as 606a-g in FIG. 6E.

At least some subsets of the items, as subsets I_(s1) to I_(s5), as wellas the contents of the container C1 and those containers in storage area600 g may continue to be needed at sufficient volumes—during a currentor an approaching inventory management interval—as compared to otheritems processed by the facility, to flow rack structure 600. In thisinstance, the WMS has determined that other items stored in rackstructure 600—such as those items stored in container C2 for retrievalduring an earlier phase of the current inventory management interval(and/or during a preceding one)—no longer have sufficient priority as tobe present in the same quantity, or at all, in rack structure 600. Inembodiments consistent with the present disclosure, the same vehicle 200and moveable rack 700, may be used to replace container C2 with adifferent container. An exemplary sequence of such a replacementoperation will be described by reference to FIGS. 6G to 11I.

FIG. 6E is a top plan view depicting of the illustrative embodiment ofFIGS. 6A to 6D, depicting temporary deployment of moveable rack 700 intoa position of interlocked alignment with storage location 612 of rackstructure 600. While in this position, the vehicle 200 is elevatedwithin task activity zone of rack 700 to retrieve container C2 in amanner as previously described, and then the vehicle 200 returns to theunderlying surface. Further operation of the gear wheels causes liftingof track 700 from the underlying support surface, and the vehicle 200relocates the rack 700 to the solid line position shown in FIG. 6E. Inthe illustrative embodiment of FIG. 6E, movements of the vehicle 200, aswell as those of vehicles 200 b to 200 d shown in FIG. 6E, are guided bya grid of fiducial markings, indicated at 632, which are sensed by oneor more imaging sensors of each vehicle. It should, however, beunderstood that other position tracking systems and techniques may beutilized without departing from the spirit and scope of the presentdisclosure.

AUTONOMOUS STORAGE

Referring again to FIGS. 1 and 7, the system may include a plurality ofracks 800 that optionally may be positioned to form rows or aisles 850.For instance, a first rack 800 a may be spaced apart from a second rack820 b so that an aisle 850 a is formed between the two racks. Inparticular, the first rack 820 a may be substantially parallel to thesecond rack to form an aisle having a substantially uniform width.Additionally, the system may include a plurality of racks forming aplurality of aisles 850 a,b. Although the aisles 850 a,b are illustratedin FIG. 7 as being parallel, it should be understood that if the systemincorporates a plurality of racks 800, the racks may be arranged in avariety of configurations and if the system includes a plurality ofaisles 850, the aisles need not be parallel.

One of the inventory management tasks assigned to a vehicle 200 may beto retrieve items from the storage locations 800. This task can beviewed as a series of sub-tasks which include exiting the current orstarting location of the vehicle, traversing a path which takes thevehicle between the starting location to an intermediate destinationadjacent a point of entry into the array of storage locations and, atthe intermediate destination, aligning the vehicle 200 with the point ofentry. As a further sub-task of the retrieval task, the aligned vehicleenters the array and maintains its alignment until it reaches the columnwithin which the vehicle is positioned, is operated to climb, accordingto yet another sub-task, until it reaches a target one of the storageareas 820. As further sub-tasks of the retrieval process, a transfermechanism of the vehicle is operated to retrieve an item, descend withinthe column until the vehicle rests upon a support surface, and then exitthe array of storage location. As a final sub-task of the retrievaloperation, the vehicle 200 proceeds along a path to an output station500, where an operator can retrieve the item from the vehicle.

Optionally, the system includes an automated element for storing andretrieving totes from the storage locations. One such automated elementis an autonomous vehicle. For example, as discussed further below, theautomated element may include a plurality of autonomous vehicles 200.Additionally, the automated vehicles 200 may be configured to transportthe totes 55 to workstations 500. At the workstation 500, one or moreitems may be removed from a tote on one of the vehicles 200. In oneembodiment, a human operator may remove an item from the vehicle.However, it should be understood that an automated mechanism may removethe item from the vehicle. Accordingly, it should be understood that theoperator that handles items at the workstation(s) 500 may be a humanoperator or an automated mechanism or a combination of the two.

The system 10 and/or various components of the system may be controllerby a central controller 450, such as a microcomputer. The centralcomputer may receive signals from various elements, such as sensors andcontrol various aspects of the system based on signals received from thevarious components. The central controller may also store data regardingthe location of various items to be retrieved from the system.Additionally, the central controller may include data regarding theidentification of items to be retrieved, such as a number of items tofill customer orders, as well as the quantify of such items. In thisway, the central controller may control and coordinate the operation ofvarious elements to schedule the retrieval and processing of a varietyof items from the storage locations.

FIG. 7 is a plan view depicting a part of an inventory management system800, which may form part of the system shown in FIG. 1 and utilizesautonomous vehicles 200 to transfer containers 55 of inventory itemsback and forth between a picking area and a vertical array of storagelocations 820. The system may incorporate a plurality of vehicles 200and the array of storage locations 820 as elements of an automatedstorage and retrieval system (AS/RS). The vehicles 200 may be configuredin the same manner as the vehicles 200 described above. However, itshould be understood that the vehicles may have modifications fordifferent tasks within the system if desired.

In any event, and turning now to FIGS. 1 and 7-13, a system for storageand retrieval of items within an array of storage locations 820 will nowbe described in detail. Turning first to FIGS. 1 and 7, a plurality ofautomated guided vehicles 200 a to 200 f are depicted being operatedwithin or about a rack structure 800. As in previously describedembodiments, the vehicles perform various item replenishment and/or itemretrieval tasks and in this instance, some of those tasks involveretrieving containers from or returning the containers (or totes) tostorage locations 820.

As discussed above, the system may include a plurality of racks that arespaced apart to form one or more aisles 850. Optionally, a track 840 maybe positioned along one or more of the racks. For instance, the trackmay be fixedly connected to the racks 800. Additionally, the track maybe configured to guide vehicles vertically so that the vehicles may beconveyed up and down the column to the storage locations in the column.Additionally, it may be desirable to position a first track along a rackon one side of the aisle, such as along rack 800 a and a second trackalong a rack on the opposite side of the aisle, such as along rack 800b. The vehicles 200 may be configured so that the vehicle travels in theaisle 850 a traveling with one side of the vehicle travelling verticallyalong a track 840 a on rack 800 a while simultaneously a second side ofthe vehicle travels vertically along a track 840 b on rack 800 b.

Each column may be formed by a plurality of vertical posts 815. Theposts may be arranged so that a plurality of vertical posts are alignedin a parallel relation on one side of the column and a plurality ofposts may be arranged in parallel relation on a second side of thecolumn opposing the posts on the first side, as shown in FIGS. 8-10. Asshown in FIG. 8, the posts 815 on each side may be interconnected by aplurality of horizontal members 817 that extend along the depth of thecolumn.

The horizontal members 817 may be separate elements solely providingstructural support for the column. Alternatively, the horizontal membersmay also support items stored in the storage locations 820. Forinstance, the horizontal supports may be planar elements forming shelvesso that the shelves form storage locations. However, it should beunderstood that the horizontal supports may be any of a variety ofconfigurations. For instance, in the embodiment illustrated in FIG. 9,the horizontal members are L-shaped brackets 817 that form elongatedhorizontal ledges to support edges of the totes 55 along the depth ofthe storage location. The horizontal brackets may be spaced apart fromone another up the height of the vertical legs 815 to form a column ofvertically spaced apart storage locations 820.

The column 810 of rack 800 has a depth, which from the perspective ofFIG. 8 is similar to the length of horizontal bracket 817. The column810 have a depth that is at similar to the length of a tote 55 orgreater. For instance, the column may have a depth sufficient toaccommodate at least one tote. However, the tote may overhang into theaisle 850, so the column may have a depth that is slightly less than thelength of a tote. Alternatively, the column may have a depth sufficientto accommodate a plurality of totes arranged end to end as shown in FIG.8. In the example illustrated in FIG. 8, the racks are sufficiently deepso that each storage location 820 can accommodate three totes 55 alignedend to end, wherein each tote is approximately similar of the length ofthe vehicles 200.

As described above, the vehicle has a length and a width. As shown inFIG. 2B, optionally the vehicle has a length “L” that is sufficientlygreater than its width “W2”. Referring to FIGS. 7-11, the rack 800 isconfigured so that each column 810 has a width that is significantlyless than its depth. Specifically, the width of each column is similarto the width of the vehicle and the depth of the column is substantiallygreater than the length of the vehicle. Optionally, the column has adepth that is more than twice the width of the vehicle as shown in FIGS.8 and 10. Additionally, the depth of the column may optionally begreater than the length of the vehicle.

FIG. 8 illustrates a plurality of vehicles in different orientationsrelative to the racks 800 and the storage locations 820. For instance, afirst vehicle 200 a is oriented for horizontal movement along path 860c, transverse the length of aisle 850. A second vehicle 200 b isoriented for horizontal movement under the rack along path 860 b that isparallel to the length of the aisle 850. Additionally, a third vehicle200 c is positioned within the aisle 850 to climb vertical tracks alongthe racks 800 on either side of the aisle. A fourth vehicle 200 d isalso positioned within the aisle and has climbed up the track 840 a,b toa storage location 820 in an upper portion of the column 810. Finally, afifth vehicle 200 f is positioned under the rack 800 and is oriented atan intermediate position between the orientation of vehicle 200 a andthe orientation of vehicle 200 b. In particular, the racks may beconfigured to facilitate the vehicles turning horizontally underneaththe racks. The fifth vehicle 200 f illustrates the vehicle in theprocess of turning under the rack from a first path to a second path.

As mentioned above, structure 800 is dimensioned and arranged such thatthe vehicles may enter and exit from various locations beneath thestorage locations, allowing for flexibility in the installation ofpicking and/or replenishing stations. If the system utilizes one or morevehicles and one or more racks, the racks may be configured to allow thevehicles to travel under the racks 800 as well as being able to travelacross or along one or more aisles that may be incorporated into thesystem. For instance, referring to FIG. 7, the vehicles may follow apath that moves along one or more path segments that may be parallel ortransverse to the aisle. A first such path is designated as path 860 a.Path 860 a is within and parallel to the length of aisle 850 a. A secondsuch path is designated path 860 b, which is parallel to the length ofaisle 850 a, but spaced apart from the aisle. Specifically, path 860 bis located under rack 800 b. Rack 800 b may be configured to provideclearance for movement of the vehicle under the lowermost storagelocation 820 so that the vehicle may travel under the rack 800 b along apath 860 b that is parallel to the length of the aisle. A third path isdesignated 860 c, which is transverse 860 a and 860 b. As shown in FIGS.8, path 860 c is parallel to the depth of the column 810.

Referring to FIGS. 8 and 10, the rack is optionally configured so thatthe columns of the rack have a depth sufficient to provide multiplepaths under each column that are substantially parallel to the length ofthe aisle 850. Specifically, as shown in FIG. 8, the posts 815 adjacentthe aisle 850 may be spaced apart from the posts 815 remote from theaisle to form an opening having a width that is greater than twice thewidth of the vehicle.

FIG. 10 illustrates vehicle 200 b moving along path 860 that is parallelto the aisle and vehicle 200 c moving along path 860′ that is parallelto path 860. Preferably path 860′ has a centerline that is spaced apartfrom the posts 815 adjacent the aisle by a distance that is greater thanhalf the length “L” of the vehicle 200 (see FIG. 2B). Similarly,preferably path 860 has a centerline that is spaced apart from the postsat the rearward edge of the column remote from the aisle 850 by adistance that is greater than half the length of the vehicle.

Optionally, the paths 860, 860′ under the rack that are parallel to theaisle may be spaced apart to provide a gap to allow a first vehicletravelling along path 860 to pass a second vehicle positioned along path860′, such as a vehicle travelling in an opposite direction along path860′. For instance, path 860 may be spaced apart from path 860′ by adistance greater than the width “W2” of vehicle 200 (see FIG. 2B).

Additionally, as discussed above, the vehicles may change direction byrotating about a vertical axis of rotation that passes through thevehicle. In particular, the axis of rotation may pass through the centerof the vehicle. The columns 810 preferably have a depth sufficient tofacilitate the vehicle rotating about the axis of rotation while thevehicle is positioned in the column under the rack. Specifically, eachof path 860, 860′ is preferably spaced apart from the posts 815 adistance greater than the distance from the axis of rotation to each ofthe corners of the vehicle.

When the vehicle turns under the rack 800, the vehicle may turn in anyof a variety of angles. Optionally, the vehicle may turn in incrementsof 90 degrees. In particular, optionally, the vehicle turns either 90degrees or 270 degrees after exiting the aisle so that the vehicletravels parallel to the aisle under the rack after climbing the track inthe aisle.

FIG. 9 is a side elevation view depicting the rack structure 800 thatincludes a plurality of columns 810 a-810 f populated within a number ofcontainers or totes, including totes T_(a), T_(b), T_(c) and T_(d). Aplurality of vehicles operating to perform various item replenishmentand/or item retrieval tasks as part of the inventory management system.Vehicle 200 a is shown having entered the leftward most drive column 810a. In this regard, and with reference now to FIG. 10, it will be seenthat the structure 800 may incorporate an array of parallel guide rails,as rails R1 and R2, which define a gap g_(G) between them. The gap isdimensioned and arranged to receive corresponding alignment structureson the vehicles to enable entry, exit and reorientation of the vehicleswithout damage to each other and the rack structure as discussed furtherbelow.

Optionally, the system may also include one or more guides 880 to guideor align the vehicles as they travel. For instance, referring to FIGS.2E and 10, the guide 880 may include a channel or groove and the vehiclemay include a corresponding guide element 235 that cooperates with theguide 880 to control movement of the vehicle 200. One example of a guideelement is a follower 235. The follower may be any element configured toengage with or cooperate with the guide 880. In the present instance,the vehicle 200 includes a central follower 233 that includes arotatable element such as a bearing that rotates about a vertical axis.Optionally, the follower 233 includes a shaft so that the followerprojects away from a surface of the vehicle, such as downwardly from alower surface of the vehicle. The central follower 233 engages thechannel in the guide 880 to constrain horizontal movement of thevehicle.

Optionally, the vehicle may also include one or more lateral guidemember 235. The lateral guide members 235 may cooperate with an outersurface of the guide 880 to constrain movement of the vehicle. Forinstance, guides 880 may comprises circular guides having acircumferential surface for guiding the rotation of the vehicles. Thevehicle may have a pair of lateral guide members 235 spaced apart fromone another a distance equal to the diameter of the circumferentialsurface of the guide. In this way, the lateral guides 235 engage thecircumferential surface of the guide to constrain the vehicle torotational motion.

Referring to FIG. 10, optionally the guide 880 includes a plurality ofintersecting guideways. For instance, guide 880 may include a firstguideway 882 in the form of a groove or channel having walls spacedapart a distance substantially similarly to the width of centralfollower 233 of the vehicle. The first guideway 882 may be oriented sothat it extends parallel to pathway 860. Additionally, guide 880 mayhave a second guideway 884 in the form of a groove or channel have wallsspaced apart a distance substantially similar to the width of thefollower 233 of vehicle 200. The second guideway 884 may be oriented sothat it extends transverse pathway 860. In the present instance,guideway 884 extends substantially perpendicular to pathway 860. In thisway, the first and second guideways 8828, 884 of guide 880 extend in alinear direction that is preferably parallel or perpendicular to theaisle 850.

Guide 880 may optionally include a non-linear guideway. For instance,the perimeter of the guide may form a non-linear guide surfaceidentified as 886 in FIG. 10. Specifically, the guide may have asubstantially circular profile forming a circumferential bearingsurface. The diameter of the circular profile may have a diametercorresponding to the distance between lateral guides 235 of the vehicle200 (see FIG. 2D).

The guideways of the guide 880 optionally intersect to facilitatechanging the direction of travel for the vehicle. For instance, guideway882 may intersect guideway 884 to facilitate the vehicle changingdirection from parallel to the aisle to perpendicular to the aisle orvice versa. The guideways 882, 884 may intersect at a center point ofthe guide. In this way, the guide may facilitate rotation of the vehicleabout a vertical axis to turn the vehicle from one direction of travelalong guideway 882 to a second direction of travel along guideway 884.

The guide 880 may guide the vehicle 200 to change direction as follows.The vehicle may move along a linear path with central follower 884engaging guideway 882 or 884 to impede lateral displacement away fromthe linear path. The vehicle travels in a horizontal direction along thelinear path until the central follower is positioned at the center pointof the guide with the lateral guides 235 of the vehicle engaging thecircumferential guideway 886. The vehicle 200 is rotated above avertical axis to change the direction of travel. For instance, drivewheel 252 a may be rotated in a first direction while drive wheel 252 bis rotated in a second direction that is reverse of the first directionto perform a zero radius turn. While the drive wheels 252 a,b rotate thevehicle about the axis of rotation, the lateral guides 235 impedelateral displacement of the vehicle away from the rotational path.

Optionally, the guides 880 are aligned with the columns to facilitaterotation of the vehicle within the column while aligning the width ofthe vehicle with the opening between posts 815 at the front of thecolumn (adjacent the aisle 850) or at the back of the column (remotefrom aisle 850).

Optionally, as shown in FIG. 10, the system may include a floor mountedlateral alignment system 890 which consists of a pair of plate membersseparated by gap g_(G). In this instance, the gap defined by alignmentsystem 890 is oriented with those defined by alignment system 895 so asto permit a vehicle to quickly and easily traverse the entire width ofthe structure while maintaining a generally constant angular orientationwithin the drive columns D1 to D6.

As described above, a plurality of guide elements, such as trackelements 840 may be attached to the rack 800 to guide the vehicles intoalignment with storage locations positioned above the floor. Forinstance, the track 840 may comprises a plurality of vertical sections.Specifically, a vertical track section may be attached to each postwithin the aisle 850. Referring to FIG. 11, the vertical track sectionmay have a profile for engaging the vertical drive system 220 of thevehicle. For instance, the track may include a plurality of teethforming a rack extending up the height of the post 815.

As shown in FIG. 11, the track 840 may straddle the aisle so that afirst track extends vertically upwardly along a first side of the columnand a second track extends upwardly along a second side of the column.For instance, column D1 and vehicle 200 e of FIG. 10 are illustrated inFIG. 11. Column D1 includes two spaced apart vertical posts 815 formingan opening having a width. Specifically, a first post has a firstvertical edge E1 and a second vertical edge E2; and a second post has afirst vertical edge E3 and a second vertical edge E4. The distancebetween vertical edges E2 and E3 is greater than the width W1 of thevehicle (see FIG. 2D). Optionally, the distance between vertical edgesE2 and E3 is less than the width W2 of the vehicle (see FIG. 2D). Inthis way, the column width may be less than the distance between theouter tips of the gears of the vertical drive 220 of vehicle 200.Accordingly, the majority of the column may be narrower than the widthof the vehicle at its widest point.

Optionally, the track 840 may be configured so that a first edge of thetrack projects toward a first column to provide a guide surface for thefirst column and a second edge of the track projects toward a secondcolumn to provide a guide surface for an adjacent column. For instance,track 840 may provide a first set of teeth projecting toward column D1and a second set of teeth projecting toward column D2.

Additionally, the vertical posts 815 may optionally be configured toprovide a stop to impede lateral displacement of the vehicle as thevehicle climbs the track 840. For instance, referring to FIG. lithe post815 overlaps with the teeth of track 840 so that edge E3 of post 815extends beyond the root of the teeth of the track and preferably towardthe crests of the track. In this way, the teeth of the vertical drive220 mesh with the track while the post impedes the vertical drive fromdisplacing laterally parallel to the depth of the column.

The vertical drive 220 of the vehicle 200 may be configured so that thevertical drive gears 220 are displaceable inwardly to reduce thedistance between the vertical drive gears. In this way, the drive gearscan be moved inwardly to provide clearance between the tracks 840 andthe vertical drive gears as the vehicle drives into the column.Alternatively, as described above, the vertical drive gears may bemounted on shafts so that the axis of rotation of each vertical gear issubstantially parallel to the horizontal direction of travel.Additionally, the axes of rotation of the vertical drive gears may besubstantially fixed so that the lateral distance between each pair ofvertical drive gears is substantially fixed. To enter the column, theteeth of the vertical drive teeth are aligned with the teeth in thetrack 840 so that the teeth of the vertical drive gears pass through theteeth in the track.

Referring to FIG. 11, the track 840 and the vertical drive gear 220 maybe aligned so that the vertical drive gears do not impinge upon orcontact the track when the vertical gear is translated relative to thetrack. For instance, the spacing between the teeth of track 840 providessufficient clearance for the teeth of the vertical drive gear 220 topass between the gaps between the teeth of track 840 when the verticaldrive gear translates horizontally along a line that is parallel to theaxis of rotation of the vertical drive gear 220. More specifically, thevertical drive gear and the track may be configured and positioned sothat the addendum circle of the vertical drive gear 220 overlaps withthe addendum line of the teeth in the track 840. While the addendumcircle of the drive gear overlaps the addendum line of the track, theteeth of the gear are configured and oriented so that the vertical drivegear passes through the gaps between teeth in the track 840.

Referring again to FIG. 11, optionally, the vertical drive gear 220 andthe track 840 may be configured and oriented to increase the clearancefor the vertical drive gear to pass through the track when the vehicledrives the opening between the vertical posts 815 forming the width ofthe column (i.e. when the vertical drive gear translates so that theaxis of rotation of the vertical drive gear translates in a horizontaldirection perpendicular to the aisle). For instance, the track 840 mayhave an upper portion and a lower portion 842. The upper portion mayhave a tooth pitch and configuration to mate with the teeth of thevertical drive gear 220. The lower portion 842 may have a tooth pitchthat is substantially similar to the tooth pitch of the upper section,but the tooth profile of the lower section may be substantiallydifferent than the upper section. For instance, the teeth of the lowersection may be substantially narrower than the teeth of the uppersection. For instance, the teeth may be at least 10% narrower andpreferably at least 20% narrower. Optionally or additionally, the teethof the lower section 842 may have dedendum that is substantially greaterthan the dedendum of the upper section. For instance, the dedendum ofthe lower section may be greater than the upper section so that the rootof the teeth extends inwardly away from the drive gears a greaterdistance than the root of the teeth of the upper section. For instance,the dedendum of the teeth of the lower section may be 10% greater andpreferably is 20% greater.

Additionally, the lower section 842 may optionally have a tapered pitchline so that the clearance between adjacent teeth gradually diminishesas the teeth progress up the height of the lower section. In otherwords, the clearance 845 between adjacent teeth at the bottom of thelower section is greatest and the spacing between adjacent teeth at theupper part of the lower section is at a minimum and the clearancegradually decreases from the maximum to the minimum.

Optionally, the posts 815 may have a variable width to facilitate thevertical drive passing through the opening between the posts 815. Forinstance, as described above, posts 815 may have a first width so thatthe edge E3 of the post extends beyond the root of the teeth of thetrack. Additionally, the lower portion 816 a,b of the post 815 may havea reduced width relative to the upper portion of the post. Specifically,the post may have a reduced width so that the edge of the postterminates below the root of the tooth. In this way, the lower portionof the post has a width that is narrower than the upper portion of thepost. Similarly, the distance between lower post 816 a and lower post816 b is greater than the distance between edge E2 and edge E3.Additionally, the opening to the column between lower portion 816 a and816 b is greater than the widest width W2 of the vehicle.

Configured as described above, the vertical drive 220 may optionally beconfigured to pass through openings in the track so that the verticaldrive is aligned with the track. After the vertical drive is alignedwith the track, the vertical drive is positioned to cooperate with thetrack to raise the track and/or to climb the track as described furtherabove.

As noted above, a central controller 450 may provide control signals forcontrolling the vehicles 200. For instance, the central controller maycontrol the operation of a vehicle to follow a path through the rack toretrieve a tote 55 from a storage location 820 in one of the columns 810in the rack 800. The vehicle may follow a path along the ground to alignthe width of the vehicle with a path that extends through an openingbetween two vertical posts 815 of the rack 800. The vehicle may travelalong the path crossing through a plurality of columns in the rack.Optionally, the central controller may provide signals to control asecond vehicle so that the second vehicle travels along a second pathparallel to the first path and under the same rack as the first vehicleso that the second vehicle passes the first vehicle under the rack.

After the vehicle passes through a plurality of columns under the rack,the vehicle reaches the column in the rack the select storage locationis located. The central controller provides signals to stop the forwardprogress of the vehicle along the path. The central controller providessignals to turn the vehicle under the rack to align the vehicle with anopening in the column. After turning, the vehicle advances along a pathparallel to the depth of the column so that the vehicle passes throughthe opening in the column and into the aisle. Optionally, the step ofadvancing the vehicle into the aisle includes the step of aligning avertical drive element with gaps in the opening in the column. Once inthe aisle, the vehicle is driven vertically upwardly until the vehicleis aligned with the desired storage location. The vehicle actuates atransfer mechanism to transfer an item from the storage location on thevehicle. Optionally, the storage location may include an item at thefront edge of the storage location separating the vehicle from thedesired item in the storage location. Accordingly, the vehicle maytransfer the item at the front edge onto the vehicle, which in turnpulls the desired item to the front edge of the storage location. Thevehicle is then driven vertically to a storage location having an openlocation for receiving an item. The vehicle then transfers the itemtoward the open location. The vehicle the moves vertically to thestorage location having the desired item and drives the transfermechanism to transfer the desired item onto the vehicle. Afterretrieving the desired item, the vehicle actuates the vertical drivemechanism to drive down the column until the vehicle engages ahorizontal drive surface, such as the floor. The horizontal drive of thevehicle is engaged to drive the vehicle through the opening in thecolumn in a direction transverse the aisle. After driving out of theaisle, the vehicle continues to drive in a horizontal direction to exitthe rack 800. For instance, the vehicle may continue along a pathtransverse the aisle 850 and pass under one or more additional racks 800and cross one or more additional aisles 850. Following such a path, thepath of the vehicle is controlled so that the width of the vehicle isaligned with the opening in each column that the vehicle passes through.Alternatively, the vehicle is rotated around a vertical axis to turn thevehicle while into alignment with a path parallel with the aisle whilethe vehicle remains under the rack. The vehicle then crosses under oneor more columns of the rack 800 until the vehicle exits from under therack.

After the vehicle exits the rack 800, the central controller 450 maycontrol the vehicle to direct the vehicle to one of a plurality ofworkstations 500. At the workstation the item is presented to anoperator to remove one or more items from the vehicle. The centralcontroller may then control the vehicle to direct the vehicle along apath to store the item it is carrying in an open storage place in therack and retrieve a subsequent item at a different storage location. Inthis way, the central controller provides control signals to a pluralityof vehicles to direct the vehicles along one of a plurality of paths toretrieve a plurality of items from the storage locations and deliveritems to the workstation 500.

CONTROL PROCESS

FIG. 12 is a block diagram depicting the subsystems of a plurality ofguided vehicles 200-1 to 200-n, according to one or more embodiments.Each vehicle, as vehicle 200-1 may comprise a Central Processing Unit(CPU) 103, a memory 105, and communication interfaces. In someembodiments, the communication interfaces comprise one or more wirelesstransceivers compliant with corresponding wireless transmissionprotocol(s) such as IEEE 802.11, with the interfaces of a vehicle beingused to communicate with other vehicles, as in a peer-to-peer topology,or with a central controller. In the latter regard, vehicles 200-1 to200-n may include position sensors 280 and object sensors 282 and usethe interfaces to communicate sensed information with a mastercontroller, such as central controller 450. The position sensors, in oneor more embodiments, include onboard imaging sensors for determiningwhen the vehicle has passed over a fiducial marking positioned on anunderlying support surface. Alternatively, however, the vehicles 200-1to 200-n may utilize signal triangulation and/or any other conventionaltechnique for determining their respective locations relative to oneanother or enabling the controller to do so.

Each vehicle 200-1 includes a power supply 288 which may, for example,be a rechargeable power supply comprising ultracapacitors, one or morebatteries, or a combination of these. In one or more embodiments, thepower supply drives a first motor 230 of first drive system. First drivesystem may further include gear wheels driven by the first motor andused, for example, to drive the vehicle vertically. In the presentinstance, the power supply 288 also supplies power to a second drivesystem, which includes a second motor 250 a and, optionally, a thirdmotor 250 b.

The CPU 286 may comprise one or more commercially availablemicroprocessors or microcontrollers that facilitate data processing andstorage. Various support circuits facilitate the operation of the CPU286 and include one or more clock circuits, power supplies, cache,input/output circuits, and the like. The memory 287 comprises at leastone of Read Only Memory (ROM), Random Access Memory (RAM), disk drivestorage, optical storage, removable storage and/or the like.

FIG. 13 is a block schematic diagram of a controller 450 which may beresponsive to instructions received from a warehouse automation system(WMS) 1440 to coordinate the assignment and performance of inventorymanagement task activities by a plurality of vehicles and subassemblies(e.g. moveable track 700 or flow rack 600), such as those assigned toAGV task groups 902-1, 904-1, 906-1 and 908-1. The controller 450comprises a Central Processing Unit (CPU) 951, support circuits 955, amemory 952, user interface components 954 (which may include, forexample, a display with touch sensitive screen or a separate keyboard),and communication interfaces 953. In some embodiments server 450comprise one or more wireless transceivers compliant with correspondingwireless transmission protocol(s) such as IEEE 802.11.

The CPU 951 may comprise one or more commercially availablemicroprocessors or microcontrollers that facilitate data processing andstorage. The various support circuits 955 facilitate the operation ofthe CPU 951 and include one or more clock circuits, power supplies,cache, input/output circuits, and the like. The memory 952 comprises atleast one of Read Only Memory (ROM), Random Access Memory (RAM), diskdrive storage, optical storage, removable storage and/or the like. Insome embodiments, the memory 952 comprises an operating system 956 andone or more inventory management applications. In some embodiments, theinventory management applications include a task agent manager module960, an AGV traffic management module 970, a state/event monitoringmodule 980, and a data repository 990.

In one or more embodiments, the task agent manager 960 is configuredwith an inventory management task processor 961, a dynamic inventoryslotting analyzer 962, a subtask sequence identifier 963, a taskpriority manager 964, an event notification detector 965, a statetransition detector 966, and an AGV selector 967. The inventorymanagement task processor 961, through execution of instructions by CPU951, processes inventory management task requests received from the WMS940.

In some embodiments, traffic management of the AGVs is performed by atraffic management module 470 of controller 450. In such cases,position, speed and direction data is collected from the vehicles atregular intervals by the controller. The position data is analyzed, andpath segment selector 474 selects paths for each vehicle over the nextcontrol interval to ensure that there are no collisions with othervehicles, with personnel, or with fixed structures. The updatedinstructions corresponding to the path selections, inclusive of headingand direction, are transmitted by the controller back to the vehicles.In other embodiments, however, the vehicles do not rely on thecontroller for relative positioning instructions, but rather solely fordestination and task assignments, with the vehicles instead relying oninternal data gathering and spatial analysis capabilities.

To facilitate the aforementioned operations, the controller 450 of FIG.13 includes a data repository which reflects an up to date location ofall inventory items for which management and allocation responsibilityhas been assigned by the WMS, as well as a map of the vehicle locationswithin the facility. In addition, to facilitate the scheduling ofpreventive maintenance procedures, usage statistics are collected forall AGVs having moving parts, so that at regular intervals, parts can beinspected, lubricated, and/or replaced.

The order of methods described herein may be changed, and variouselements may be added, reordered, combined, omitted, modified, etc. Allexamples described herein are presented in a non-limiting manner.Various modifications and changes may be made as would be obvious to aperson skilled in the art having benefit of this disclosure.Realizations in accordance with embodiments have been described in thecontext of particular embodiments. These embodiments are meant to beillustrative and not limiting. Many variations, modifications,additions, and improvements are possible. Accordingly, plural instancesmay be provided for components described herein as a single instance.Boundaries between various components, operations and data stores aresomewhat arbitrary, and particular operations are illustrated in thecontext of specific illustrative configurations. Other allocations offunctionality are envisioned and may fall within the scope of claimsthat follow. Finally, structures and functionality presented as discretecomponents in the example configurations may be implemented as acombined structure or component. These and other variations,modifications, additions, and improvements may fall within the scope ofembodiments as defined in the claims that follow.

Accordingly, while the foregoing is directed to embodiments of thepresent invention, other and further embodiments of the invention may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

We claim:
 1. A material handling vehicle for conveying items betweendesired locations cooperable with a storage assembly positioned along awork surface having a plurality of storage locations for storing aplurality of items and a moveable track moveable relative to the worksurface into desired positions relative to the storage assembly foralignment with desired storage locations, the track extending in avertical direction relative to the work surface for alignment withelevated storage locations, comprising: a transfer mechanism fortransferring items between the vehicle and the storage locations; avertical drive assembly configured to engage and lift the moveable trackin a direction away from the work surface to facilitate movement of thetrack relative to the work surface and configured to engage the trackand drive the vehicle along the track into alignment with a desiredstorage location of the storage assembly for transfer of items by thetransfer mechanism between the vehicle and the desired storage location;a surface drive assembly configured to drive the vehicle along the worksurface and into operable engagement with the track so that the verticaldrive assembly operates to engage and lift the track and the surfacedrive assembly operates to drive the vehicle with the lifted track intoa desired position relative to the storage assembly for the track toalign with elevated storage locations; and a power source for poweringthe vertical drive assembly and the surface drive assembly.
 2. Thevehicle of claim 1 wherein the surface drive assembly comprises aplurality of wheels engageable with the work surface.
 3. The vehicle ofclaim 1 wherein the vertical drive comprises a plurality of gears spacedapart from one another wherein each gear comprises teeth configured toengage the track.
 4. The vehicle of claim 3 wherein vertical drivecomprises a motor connected with the plurality of gears and operable tosynchronously drive the plurality of gears.
 5. The vehicle of claim 1wherein the vehicle comprises a support surface for supporting itemsretrieved from the elevated storage locations.
 6. The vehicle of claim 5wherein the support surface comprises a plurality of rollers.
 7. Thevehicle of claim 1 wherein the vertical drive is rotatable about a firstaxis and the surface drive assembly is rotatable about a second axistransverse the first axis.
 8. The vehicle of claim 7 wherein the firstaxis is spaced vertically above the second axis.
 9. The vehicle of claim1 wherein the vertical drive comprises a forward vertical driveconfigured to cooperate with a forward track and a rearward verticaldrive configured to cooperate with a rearward track.
 10. The vehicle ofclaim 9 wherein the forward vertical drive is connected with therearward vertical drive so that the forward vertical drive is drivensynchronously with the rearward vertical drive.
 11. The vehicle of claim1 wherein the vertical drive is configured to maintain four points ofcontact with the track to control the orientation of the vehiclerelative to the track when the vehicle lifts the track.